THE 


OEE  DEPOSITS 


OF   THE 


UNITED   STATES 


BY 


JAMES  F.  KEMP,  A.B.,  E.M. 

PROFESSOR  OF  GEOLOGY  IN  THE  SCHOOL  OF  MINES,  COLUMBIA  COLLEGE 


NEW  YORK 
THE   SCIENTIFIC   PUBLISHING   COMPANY 

1893 


COPYRIGHTED,  1893, 

BY 
THE  SCIENTIFIC  PUBLISHING  COMPANY. 


JOHN  STRONG  NEWBEKRY* 

FIRST  PROFESSOR   OF  GEOLOGY  IN  THE   SCHOOL.  OF  MIXES,    COLUMBIA  COLLEGE 

THIS    BOOK    IS    RESPECTFULLY    INSCRIBED    BY 

HIS    OLD    STUDENT    AND    FRIEND 

THE  AUTHOR 


*DR.  NEWBERRY  died  while  the  book  was  in  press. 


PREFACE. 


The  following  pages  presuppose  for  their  comprehension  some 
acquaintance  with  geology  and  mineralogy.  The  materials  for 
them  have  been  collected  and  arranged  in  connection  with  lectures 
on  economic  geology,  first  at  Cornell  University  and  later  at  the 
School  of  Mines,  Columbia  College.  To  the  descriptions  of  others 
the  author  has  endeavored  to  add,  as  far  as  possible,  observations 
made  by  himself  in  travel  during  the  last  ten  years.  The  purpose 
of  the  book  is  twofold,  and  this  fact  has  been  conscientiously  kept 
in  view.  It  is,  on  the  one  hand,  intended  to  supply  a  condensed 
account  of  the  metalliferous  resources  of  the  country,  which  will 
be  readable  and  serviceable  as  a  text-book  and  work  of  reference. 
For  this  reason  every  effort  has  been  put  forth  to  make  the  bibliog- 
raphy-complete, so  that,  in  cases  where  fuller  accounts  of  a  region 
are  desired,  the  original  sources  may  be  made  available  in  any 
good  library.  But,  on  the  other  hand,  it  has  also  been  the 
hope  and  ambition  of  the  author  to  treat  the  subject  in  such  a  way 
as  to  stimulate  investigation  and  study  of  these  interesting  phe- 
nomena. If,  by  giving  an  extended  view  over  the  field,  and  by 
making  clear  what  our  best  workers  have  done  in  late  years  toward 
explaining  the  puzzling  yet  vastly  important  questions  of  origin 
and  formation,  some  encouragement  may  be  afforded  those  in  a 
position  to  observe  and  ponder,  the  second  aim  will  be  fulfilled. 
In  carrying  out  this  purpose,  the  best  work  of  recent  investigators 
on  the  origin  and  changes  of  rocks,  especially  as  brought  out  by 
microscopic  study,  has  been  kept  constantly  in  mind,  and  likewise 
in  the  artificial  production  of  the  ore  and  gangue  minerals.  So 
much  unsound  and  foolish  theorizing  has  been  uttered  and  believed 
about  ores,  that  too  much  care  cannot  be  exercised  in  basing  ex- 
planations on  reasonable  and  right  foundations. 

Acknowledgments  are  due  to  many  friends  for  encouragement, 
suggestion,  and  criticism.  To  Prof.  Henry  S.  Williams,  now  of 


iv  PREFACE. 

Yale,  but  late  of  Cornell,  whose  interest  made  the  book  possible, 
these  are  especially  to  be  made.  On  particular  regions  much  ad- 
vice has  been  obtained  from  Dr.  W.  P.  Jenney,  for  which  the 
author  is  grateful.  In  the  same  way  Prof.  H.  A.  Wheeler  of  St. 
Louis,  Prof.  R.  A.  F.  Penrose  of  Chicago,  and  several  other  friends 
have  contributed.  Dr.  R.  W.  Raymond  suggested  the  method  of 
enumerating  the  paragraphs.  It  has  the  advantages  of  being  elas- 
tic and  of  showing  at  once  in  what  part  of  the  book  any  paragraph 
is  situated. 

•The  geologists  of  the  United  States  Geological  Survey,  who 
have  been  engaged  in  the  study  of  our  great  mining  regions,  es- 
pecially in  the  West,  have  laid  the  whole  scientific  world  under 
a  debt  of  gratitude,  and  in  this  country  have  probably  been  the 
most  potent  influences  toward  right  geological  conceptions  regard- 
ing ores.  Of  writers  abroad,  Von  Groddeck  has  been  a  means  of 
inspiration  to  all  readers  of  German  who  have  interested  them- 
selves in  this  branch  of  geology.  The  writer  cannot  well  forbear 
acknowledging  their  influence. 

Should  errors  be  noted  by  any  reader,  the  author  will  be  very 
appreciative  of  the  kindness  if  his  attention  is  called  to  them. 

J.  F.  KEMP. 

COLUMBIA  COLLEGE, 
IN  THE  CITY  OF  NEW  YORK. 


TABLE   OF    CONTENTS 


PAGE 

PREFACE iii 

LIST  OF  ILLUSTRATIONS xi 

LIST  OF  ABBREVIATIONS...  xv 


PART  I.— INTRODUCTORY. 

CHAPTER  I. — GENERAL  GEOLOGICAL  FACTS  AND  PRINCIPLES. 

The  two  standpoints  of  geology,  3-4  ;  the  scheme  of  classifica- 
tion, 4-5  ;  classification  of  rocks,  6  ;  brief  topographical  survey  of 
the  United  States,  6-7 ;  brief  geological  outline,  7-10 ;  the  forms 
assumed  by  rock  masses,  10,  11 1-11 

CHAPTER  II.— ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS. 

By  local  contraction,  12,  13 ;  by  more  extensive  movements, 
13-17  ;  faults,  17-20  ;  secondary  modifications  of  cavities,  20-22..  12-22 

CHAPTER  III. — THE  MINERALS  IMPORTANT  AS  ORES  ;    THE   GANGUE 
MINERALS,  AND  THE  SOURCES  WHENCE  BOTH  ARE  DERIVED. 

The  minerals,  23  ;  source  of  the  metals,  23-27 23-27 

CHAPTER  IV.— ON  THE  FILLING  OF  MINERAL  VEINS. 

Resume,  28;  methods  of  filling,  28,  29;  ascension  by  infiltra- 
tion, 29,  32  ;  lateral  secretion,  30,  31 ;  replacement,  33,  34 28-34 

CHAPTER  V.— ON  CERTAIN  STRUCTURAL  FEATURES  OF  MINERAL  VEINS. 

Banded  structure,  35-37  ;  clay  selvage,  37  ;  pinches,  swells,  and 

lateral  enlargements,  37 ;  changes  in  the  character  of  the  vein 

filling,  38 ;  secondary  alteration  of  the  minerals  in  veins,  38-40 ; 

electrical  activity,  40,  41 35-11 

CHAPTER  VI.— THE  CLASSIFICATION  OF  ORE  DEPOSITS,  A  REVIEW  AND 
A  SCHEME  BASED  ON  ORIGIN. 

Statement  of  principles,  42-44 ;  schemes  involving  only  the 
classification  of  veins  by  Von  Weissenbach,  44 ;  Von  Cotta,  44,  45  ; 
Le  Conte,  45 ;  general  schemes  based  on  form :  Von  Cotta  and 


vi  TABLE   OF  CONTENTS. 

PAGE 

Prime,  46,  47  ;  Lottner-  Serlo,  47  ;  Koehler,  47  ;  Gallon,  47  ;  schemes 
partly  based  on  form,  partly  on  origin  :  J.  D.  Whitney,  48  ;  J.  S. 
Newberry,  48  ;  J.  A.  Phillips,  49  ;  schemes  largely  based  on  ori- 
gin: J.  Grimm,  50 ;  A.  von  Groddeck,  51 ;  R.  Pumpelly,  51,  52  ; 
schemes  entirely  based  on  origin :  H.  S.  Munroe,  52,  53  ;  J.  F. 
Kemp,  53-55  ;  remarks  on  the  above,  and  discussion  of  methods 
of  formation,  56-62 ;  bibliography,  62-65 42-65 

PART  II.— THE  ORE  DEPOSITS. 

CHAPTER  I. — THE  IRON  SERIES  (IN  PART). — INTRODUCTORY  REMARKS 
ON  IRON  ORES.— LIMONITE.— SIDERITE. 

General  literature,  69-70 ;  table  of  analyses,  70  ;  general  re- 
marks, 70-73 ;  Limonite,  Example  1,  Bog  Ore,  73-75 ;  Example  2, 
Brown  Hematite,  not  Siluro-Cambrian,  75-79  ;  Example  2a,  Siluro- 
Cambrian  Limonites,  79-84;  origin  of  same,  84-85.  Analyses  of 
limonites,  86.  Siderite  or  Spathic  Ore,  introductory,  86  ;  Example 

3,  Clay  Ironstone,  86-87  ;  Example  3a,  Black-band,  87-89;  Example 

4,  Burden  mines,  89-91 ;  Example  5,  Roxbury,  Conn.,  91 69-91 

CHAPTER  II.— THE  IRON  SERIES,  CONTINUED.— HEMATITE,  RED  AND 
SPECULAR. 

Introductory  remarks,  92  ;  Example  6,  Clinton  Ore,  92-98  ;  Ex- 
ample 7,  Crawford  Co.,  Mo.,  99  ;  Example  8,  Jefferson  Co.,  N.  Y., 
99 ;  Example  9,  Lake  Superior  Hematites,  100-113 ;  introductory, 
100-102  ;  Marquette  district,  102-106  ;  Menominee,  107-108 ;  Peno- 
kee-Gogebic,  108-109  ;  Vermilion  Lake,  110-111 ;  Mesabi,  111-113 ; 
Example  10,  James  River,  Va.,  113  ;  Example  11,  Pilot  Knob.,  Mo., 
114-116  ;  Example  lla,  Iron  Mountain,  Mo.,  116-118 ;  Analyses  of 
Hematites,  118 92-119 

CHAPTER  III.— MAGNETITE  AND  PYRITE. 

Example  12,  Magnetite  beds,  120-127 ;  Adirondack  region, 
120-122 ;  New  York,  New  Jersey,  and  Pennsylvania,  123-125  ;  North 
Carolina  and  Virginia,  125 ;  Colorado,  126 ;  California,  126-127 ; 
Example  13,  Cornwall,  Penn.,  127;  Example  14,  Iron  Co.,  Utah, 
128 ;  Example  15,  Magnetite  Sands,  128 ;  origin  of  Magnetite  de- 
posits, 129-130;  distribution  of  Phosphorus,  130;  Analyses  of 
Magnetites,  131 ;  Pyrite,  131-132 ;  Example  16,  Pyrite  Beds,  131- 
132  ;  Statistics  of  iron  ores,  133 120-133 

CHAPTER  IV. — COPPER. 

Table  of  analyses  of  copper  ores,  134  ;  Example  16,  continued, 
Pyrite  Beds,  134-135 ;  Ore  Knob,  N.  C.,  135  ;  Spenceville,  Cal., 
136;  Example  17,  Butte,  Mont.,  136-137;  Gilpin  Co.,  Colo.,  138; 
Llano  Co.,  Texas,  139  ;  Example  18,  Keweenaw  Point,  Mich.,  139- 
143 ;  origin  of  the  copper,  141-142  ;  Example  19,  St.  Genevieve, 
Mo.,  143-144;  Example  20,  Arizona  copper,  144-151 ;  Morenci,  145  ; 
Bisbee,  148  ;  Globe  district,  150  ;  Santa  Rita,  N.  M.,  150-151 ;  Black 


TABLE   OF  CONTENTS.  vii 

PAGE 

Range,  151  ;  Copper  Basin,  151 ;  Example  2Qg,  Crismon-Mammoth, 
Utah,  152 ;  Sunrise,  Wyo.,  152 ;  Example  21,  copper  ores  in  Tri- 
assic  or  Permian  sandstone,  152-154 ;  Eastern  States,  152-153 ; 

Western  States,  154  ;  statistics  of  copper,  155 134-155 

/ 
CHAPTER  V. — LEAD  ALONE. 

Introductory  and  analyses,  156  ;  Example  22,  Atlantic  Border, 
St.  Lawrence  Co.,  N.  Y.,  156;  Massachusetts,  Connecticut,  and 
Eastern  New  York,  157,  158 ;  Southeastern  Pennsylvania,  157 ; 
Davison  Co.,  N.  C.,  157  ;  Example  23,  Southeast  Missouri,  158-159  ; 
statistics  of  lead,  160 156-160 

CHAPTER  VI. — LEAD  AND  ZINC. 

Example  24,  the  Upper  Mississippi  Valley,  161-164  ;  Example 
24a,  Washington  Co.,  165;  Example  246,  Livingston  Co.,  Ky.,  165; 
Example  25,  Southwest  Missouri,  166-172  ;  Example  26,  Wythe  Co., 
Va.,  172 161-173 

CHAPTER  VII.— ZINC  ALONE  OR  WITH  METALS  OTHER  THAN  LEAD. 

Introduction,  tables  of  analyses,  174;  Example  27,  Saucon 
Valley,  Penn.,  174-175;  Example  28,  Franklin  Furnace  and  Ster- 
ling, N.  J..  175-179  ;  statistics  of  zinc,  180 174-180 

CHAPTER  VIII.— LEAD  AND  SILVER. 

Introduction,  181 ;  Rocky  Mountain  Region  and  Black  Hills, 
181-193 ;  New  Mexico,  181-182 ;  Example  29,  Kelley  Lode,  181  ; 
Colorado,  182-191  ;  Example  30,  Leadville,  182-185  ;  Example  30a, 
Ten  Mile,  Summit  Co.,  185-186;  Example  306,  Monarch  district, 
186  ;  Example  30c,  Eagle  River,  186 ;  Example  30d,  Aspen,  186  and 
188-190  ;  Example  30e,  Rico,  190  ;  Example  31,  Red  Mountain,  190 ; 
South  Dakota,  Example  30/,  191  ;  Montana,  Idaho,  191-192  ;  Ex- 
ample 32,  Glendale,  191 ;  Example  32a,  Wood  River,  191-192  ;  Ex- 
ample 33,  Wickes,  192 ;  Example  34,  Cceur  d'Alene,  192  ;  region  of 
the  Great  Basin,  192-198;  Utah,  Example  35,  Bingham  and  Big  and 
Little  Cotton  wood,  192-194  ;  Example  35a,  Tooele  Co.,  194  ;  Exam- 
ple 356,  Tintic  ;  Example  30g,  Horn  Silver,  195 ;  Example  33a,  Car- 
bonate Mine,  Beaver  Co.,  195  ;  Example  326,  Cave  Mine,  Beaver 
Co.,  195;  Nevada,  Example  36,  Eureka,  196-197;  Arizona,  Cali- 
fornia, 198 181-198  ,. 

CHAPTER  IX. — SILVER  AND  GOLD. — INTRODUCTORY:  EASTERN  SILVER 
MINES  AND  THE  ROCKY  MOUNTAIN  REGION  OF  NEW  MEXICO  AND 
COLORADO. 

Introduction,  199  ;  Examples  37^12  defined,  199-200 ;  silver 
minerals,  200 ;  Example  22a,  Atlantic  Border,  201 ;  Example  42, 
Silver  Islet,  201  ;  region  of  the  Rocky  Mountains  and  the  Black 
Hills,  202-215 ;  New  Mexico,  geology,  202-203 ;  mines,  203-204 ; 
Colorado,  geology,  204-205 ;  San  Juan  region,  205-210 ;  Gunnison 


viii  TABLE   OF  CONTENTS. 

PAGE 

district,  211;  Eagle  Co.,  211;  Summit  Co.,  211;  Park,  Chaf- 
fee,  Rio  Grande,  and  Codejos  counties,  212  ;  Custer  Co.,  212-213  ; 
Gilpin,  Clear  Creek,  and  Boulder  counties,  214 199-215 

CHAPTER  X. — SILVER  AND  GOLD,  CONTINUED. — ROCKY  MOUNTAIN  RE- 
GION, WYOMING,  THE  BLACK  HILLS,  MONTANA,  AND  IDAHO. 

Wyoming,  216 ;  the  Black  Hills,  216-218  ;  Montana,  geology, 
218;  Madison,  Beaverhead,  and  Jefferson  counties,  219;  Silver 
Bow  Co.,  220-221 ;  Deer  Lodge  and  Lewis  and  Clarke  counties, 
221;  MissoulaCo.,  222;  Idaho,  geology,  222;  Custer,  Boise,  Alturas, 
and  other  counties,  223 216-223 

CHAPTER  XI. -^-SILVER  AND  GOLD,  CONTINUED. — THE  REGION  OF  THE 
GREAT  BASIN,  IN  UTAH,  ARIZONA,  AND  NEVADA. 

Utah,  geology,  224  ;  Ontario  and  other  mines,  225-226  ;  Silver 
Reef,  226-227  ;  Arizona,  geology,  227 ;  northern  counties  and  the 
Silver  King  mine,  228  ;  Tombstone,  229  ;  Pima  and  Yuma  counties, 
229  ;  Nevada,  geology,  230  ;  Lincoln  Co.,  230  ;  Ney  and  White  Pine 
counties,  231  ;  Lander  and  other  counties,  232 ;  the  Comstock 
Lode,  233-237 224-237 

CHAPTER   XII.— THE   PACIFIC   SLOPE.— WASHINGTON,   OREGON,   AND 
CALIFORNIA. 

Washington,  geology,  238  ;  mines,  239 ;  Oregon,  geology,  239  ; 
gold  quartz  and  placers,  240  ;  Example  44a,  Port  Orford,  240  ;  Cali- 
fornia, geology,  241 ;  Calico  district,  242-243  ;  Example  44,  aurifer- 
ous gravels,  243-248  ;  river  gravels,  243-245  ;  high  or  deep  gravels, 
245-248  ;  Example  45,  gold  quartz  veins,  248-251 238-251 

CHAPTER  XIII.— GOLD  ELSEWHERE  IN  THE  UNITED  STATES  AND  CAN- 
ADA. 

Example  45a,  Southern  States,  252 ;  Example  456,  Ishpeming, 
Mich.,  253  ;  Alaska,  geology,  253-254  ;  Example  46,  Douglass  Island, 
254-255  ;  Example  45c,  Nova  Scotia,  255  ;  Example  45d,  gold  else- 
where in  Canada,  256  ;  statistics,  256-257 252-257 

CHAPTER  XIV.— THE  LESSER  METALS.— ALUMINIUM,  ANTIMONY,  AR- 
SENIC, BISMUTH,  CHROMIUM,  MANGANESE. 

Aluminium,  258 ;  antimony,  259-260 ;  Example  47,  including 
California,  Nevada,  Arkansas,  and  New  Brunswick,  259  ;  Exam- 
ple 48,  Utah,  Iron  Co.,  259-260 ;  arsenic,  260 ;  bismuth,  260-261  ; 
chromium,  261 ;  Example  49,  chromite  in  serpentine,  261 ;  man- 
ganese, 262  ;  Example  50,  manganese  ores  in  residual  clay,  262-266  ; 
statistics,  266 251-266 

CHAPTER  XV. — THE  LESSER  METALS,  CONTINUED. — MERCURY,  NICKEL 
AND  COBALT,  PLATINUM,  TIN. 

Mercury,  267-269;  Example  50,  New  Almaden,  267,  268;  Exam- 


TABLE   OF  CONTENTS.  ix 

PAGE 

pie  50a,  Sulphur  Bank,  268;  Example  506,  Steamboat  Springs,  268- 
269  ;  nickel  and  cobalt,  269-272  ;  platinum,  272 ;  tin,  273-274  ;  Ex- 
ample 51,  Black  Hills,  273 267-273 

CHAPTER  XVI. — CONCLUDING  REMARKS. 

Summation  of  such  general  geological  relations  among  North 
American  ore  deposits  as  can  be  detected 275-277 

ADDENDA. — Wadsworth's  scheme  of  classification  of  ore  deposits,  279  ; 
J.  P.  Kimball  on  the  genesis  of  spathic  ores,  279  ;  bog  ores  of  the 
Three  Rivers  district,  Province  of  Quebec,  280  ;  iron  ores  of  Arkan- 
sas, 280  ;  titaniferous  magnetites,  281 ;  the  origin  of  magnetite 
as  segregated  veins,  282  ;  Cambrian  at  St.  Genevieve,  Mo.,  283 ; 
C.  R.  Boyd  on  zinc  mines  at  Austinville,  Va.,  283  ;  W.  Lindgren 
on  the  American  and  Yuba  rivers,  California,  283 ;  Posepny's 
great  paper  on  the  origin  of  ores,  283  ;  Fuchs  et  De  Launay,  Traite 
des  Gites  Mineraux  et  Metalliferes,  Paris,  1893,  285. 278-285 


LIST    OF   ILLUSTRATIONS. 


FIGS.  PAGE 

1.  Illustration  of  rifting  in  granite  at  Cape  Ann,  Mass.    After  R.  S. 

Tarr 12 

2.  Open  fissure  in  the  Aubrey  limestone  (Upper  Carboniferous)  25 

miles  north  of  Canon  Diablo  Station,  on  the  A.  &  P.  R.  R.,  Ari- 
zona.    Photographed  by  G.  K.  Gilbert,  1892 15 

3.  Normal  fault  at  Leadville,  Colo.     After  A.  A.  Blow 17 

4.  Reversed  fault  at  Holly  Creek,  near  Dalton,  Ga.     After  C.  W. 

Hayes 18 

5.  Illustration  of  one  vein  faulting  another  at  Newman  Hill,  near 

Rico,  Colo.     After  J.  B.  Farish 20 

6.  Banded  vein  at  Newman  Hill,  near  Rico,  Colo.     After  J.  B.  Farish.     36 

7.  Illustration  of  the  oxidized  zone,  or  gossan,  the  zone  of  enrichment, 

and  the  unchanged  sulphides,  at  Ducktown,  Tenn.    After  A.  F. 
Wendt 39 

8.  Section  of  the  Hurst  limonite  bank,  Wythe  Co.,  Va.,  illustrating 

the  replacement  of  shattered  limestone  with  limonite  and  the 
formation  of  geodes  of  ore.    After  E.  R.  Benton 76 

9.  Geological  section  of  the  Amenia  mine,  DutchessCo.,  N.  Y.,  illus- 

trating a  Siluro-Cambrian  limonite  deposit.    After  B.  T.  Put- 
nam       80 

10.  View  of  the  Siluro-Cambrian  brown  hematite  bank  at  Baker  Hill, 

Ala.    From  the  Engineering  and  Mining  Journal 83 

11.  Map  and  sections  of  the  Burden  Spathic  ore  mines.    After  J.  P. 

Kimball 90 

12.  Clinton  ore,  Ontario,  Wayne  Co.,  N.  Y.    After  C.  H.  Smyth,  Jr. .  93 

13.  Clinton  ore,  Clinton,  N.  Y.    After  C.  H.  Smyth,  Jr 94 

14.  Clinton  ore,  Eureka  mine,  Oxmoor,  Ala.     After  C.  H.  Smyth,  Jr.  95 

15.  Cross  section  of  the  Sloss  mine,  Red  Mountain,  Ala.    From  the  En- 

gineering and  Mining  Journal 95 

16.  Map  of  the  vicinity  of  Birmingham,  Ala.    After  W.  P.  Barker. . .     96 

17.  Open  cut  in  the  Republic  mine,  Marquette  range,  showing  a  horse 

of  jasper.    From  a  photograph  by  H.  A.  Wheeler 103 

18.  Cross  sections  to  illustrate  the  occurrence  and  associations  of  iron 

ore  in  the  Marquette  district,  Michigan.    After  C.  R.  Van  Hise.  105 

19.  Plan  of  Ludington  ore  body,  Menominee  district,  Michigan.     After 

P.  Larsson „ .  .*.  108 


xii  LIST  OF  ILLUSTRATIONS. 

FIGS.  PAGE 

20.  Cross  section  of  the  Colby  mine,  Penokee-Gogebic  district,  Mich- 

igan, to  illustrate  occurrence  and  origin  of  the  ore.     After  C.  R. 
Van  Hise 109 

21.  General  cross  section  of  ore  body  at  Biwabik,  Mesabi  Range,  Minn. 

After  H.  V.  Winchell 112 

22.  Cross  section  of  Pilot  Knob,  Mo.     From  a  drawing  by  W.  B.  Potter.  114 

23.  View  of  open  cut  at  Pilot  Knob.,  Mo.,  showing  the  bedded  char- 

acter of  the  iron  ore.     From  a  photograph  by  J.  F.  Kemp 115 

24.  View  of  Iron  Mountain,   Mo.     From  a   photograph   by  H.   A. 

Wheeler 116 

25.  Cross  section  of  Iron  Mountain,  Mo.,  showing  the  knob  of  por- 

phyry, with  the  veins  of  ore,  the  conglomerate,  etc.     After 
W.  B.  Potter 117 

26.  View  of  open  cut  and  underground  work  in  Mine  21,  Mineville, 

near  Port  Henry,  N.  Y.     From  a  photograph  by  J.  F.  Kemp. . .  121 
27a  and  27b.  Model  of  the  Tilly  Foster  ore  body.     After  F.  S.  Rutt- 

mann  and  the  model  itself 124 

28.  Cross  section  of  the  magnetite  ore  body  at  Cornwall,  Penn.     After 

Bailey  Willis 127 

29.  Illustration  of  overlapping  lenses  of  pyrite.     After  A.  F.  Wendt. .  132 

30.  Cross  section  of  the  Bob-tail  mine,  Central  City,  Colo.     After  F.  M. 

Endlich 138 

31.  Geological  sections  of  Keweenaw  Point,  Mich.,  near  Portage  Lake 

and  through  Calumet.     After  R.  D.  Irving 140 

32.  Cross  section  of  the  St.  Genevieve  copper  mine,  illustrating  the  re- 

lations of  the  ore.     After  F.  Nicholson 144 

33.  Section  at  the  St.  Genevieve  mine,  illustrating  the  intimate  rela- 

tions of  ore  and  chert.     After  F.  Nicholson 144 

34".  Geological  map  of  the  Morenci  or  Clifton  copper  district  of  Ari- 
zona.    After  A.  F.  Wendt 145 

35.  Vertical  section  of  Longfellow  Hill,  Clifton  district,  Arizona.    Af- 

ter Wendt 146 

36.  Horizontal  sections  of  Longfellow  ore  body.     After  Wendt 146 

37.  Geological  section  of  the  Metcalf  mine,  Clifton  district,  Arizona. 

After  Wendt 147 

38.  Section  of  Copper  Queen  ore  body,  Bisbee  district,  Arizona.     Af- 

ter A.  F.  Wendt 148 

39.  View  of  the  Copper  Queen  mine,  Bisbee  district,  Arizona.     From 

a  photograph  by  James  Douglass 149 

40.  Cross  section  of  the  Schuyler  copper  mine,  N.  J.     After  N.  H. 

Barton 153 

41.  Gash  veins,  fresh  and  disintegrated.     After  T.  C.  Chamberlain  . . .  162 

42.  Idealized  section  of  "  flats  and  pitches,"  forms  of  ore  bodies  in 

Wisconsin.    After  T.  C.  Chamberlain 163 

43.  Vertical  section  of  a  typical  zincblende  ore  body,  near  Webb  City, 

Mo.     After  C.  Henrich    168 

44.  View  of  the  Motley  mine,  Webb  City,  Mo.     After  a  photograph  by 

W.  P.  Jenney 169 


LIST   OF  ILLUSTRATIONS. 


FIGS. 


PAGE 

44a.  View  of  the  Bertha  zinc  mines,  Wythe  Co.,  Va.     From  a  photo- 
graph by  A.  E.  W.  Miller 173 

45.  Section  at  Franklin  Furnace,  N.  J.,  showing  the  geological  rela- 

tions of  the  f ranklinite  ore  body.     After  F.  L.  Nason 176 

46.  Section  of  the  White  Cap  chute,  Leadville,  showing  the  geological 

relations  of  the  ore,  and  its  passage  into  unchanged  sulphides 

in  depth.     After  A.  A.  Blow 184 

47.  Geological  section  of  the  Eagle  River  mines,  Colo.     After  E.  E. 

Olcott 187 

48.  Geological  section  at  Aspen,  Colo.     After  A.  Lakes 188 

49.  View  of  the  Bunker  Hill  and  Sullivan  mines,  Wardner,  Idaho. 

From  a  photograph  loaned  by  E.  E.  Olcott , 193 

50.  Section  at  Eureka,  Nev.    After  a  plate  by  J.  S.  Curtis 197 

51.  Geological  cross  sections  of  strata  and  veins  at  Newman  Hill,  near 

Rico,  Colo.     After  J.  B.  Farish 208 

52.  Geological  cross  sections  of  strata  and  veins  at  Newman  Hill. 

After  J.  B.  Farish 209 

53.  View  of  Lower  Creede,  Colo.    From  the  Engineering  and  Mining 

Journal 210 

54.  Geological  section  of  the  Black  Hills.     After  Henry  Newton 217 

55.  Cross  section  of  vein  at  the  Alice  mine,  Butte,  Mont.     After  W.  P. 

Blake 220 

56.  Two  sections  of  the  argentiferous  sandstone  at  Silver  Reef,  Utah. 

After  C.  M.  Rolker 226 

57.  Section  of  Comstock  Lode.     After  G.  F.  Becker 233 

58.  Geological  section  of  the  Calico  district,  California.     After  W. 

Lindgren 242 

59.  View  of  the  Union  diggings,  Columbia  Hill,  Nevada  Co.,  Cali- 

fornia.    From  a  photograph 243 

60.  View  of  the  Timbuctoo  diggings,  Yuba  Co.,  California.     From  a 

photograph „  244 

61.  Generalized  section  of  a  deep  gravel  bed,  with  technical  terms. 

After  R.  E.  Browne 246 

62.  Section  of  Forest  Hill  Divide,  Placer  Co.,  California,  to  illustrate 

the  relations  of  old  and  modern  lines  of  drainage.     After  R.  E. 
Browne 247 

63.  Sections  of  the  Crimora  manganese  mine,  Virginia.     After  C.  E. 

Hall 263 

64.  Geological  sections  illustrating  the  formation  of  the  manganese 

ores  in  Arkansas.     After  R.  A.  F.  Penrose.. 264 

65.  The  Turner  mine,  Batesville  region,  Arkansas.     After  R.  A.  F. 
Penrose 265 

66.  Section  of  the  Great  Western  cinnabar  mine.     After  G.  F.  Becker.  268 

67.  Horizontal  section  of  the  Etta  granite  knob,  Black  Hills.     After 

W.P.Blake..  .  273 


, 


ABBREVIATIONS. 


A.  A.  A.  &— Proceedings  of  the  American  Association  for  the  Advance- 
ment of  Science. 
A.  G.  or  Amer.  Geol. — American  Geologist,  Minneapolis,  Minn. 

A.  J.  S.  or  Amer.  Jour.  Sei. — American  Journal  of  Science,  also  known 

as  Silliman's  Journal.    Fifty  half-yearly  volumes  make  a  series. 

The  Journal  is  now  (1893)  in  the  third  series.    In  the  references  the 

series  is  given  first,  then  the  volume,  then  the  page. 
Ann.  des  Mines. — Annales  des  Mines.    Paris,  France. 
Bost.  Soc.  Nat.  Hist. — See  Proceedings  of  same. 
Bull  Geol.  Soc.  Amer.  or  G.  S.  A.—  Bulletin  of  the  Geological  Society  of 

America. 
Bull.  Mus.  Comp.  Zool. — Bulletin  of  the  Museum  of  Comparative  Zoology, 

Harvard  University.     Cambridge,  Mass. 

B.  und  H.  Zeitung. — Berg-  und  Huettenmdnnische  Zeitung.    Leipzig, 
Germany. 

M.  E. — Transactions  of  the  American  Institute  of  Mining  Engineers. 

Neues  Jahrb. — Neues  Jahrbuch  fiir  Mineralogie,  Geologie  und  Palaeon- 
tologie,  often  called  Leonhard's  Jahrbuch.  Stuttgart,  Germany. 

Oest.  Zeit.f.  Berg-  u.  Huett.—Oesterreichische  Zeitschrift  fur  Berg-  und 
Huettenwesen.  Vienna,  Austria. 

Phil.  Magazine. — Philosophical  Magazine.    Edinburgh,  Scotland. 

Proc.  Amer.  Acad. — Proceedings  of  the  American  Academy  of  Arts  and 
Sciences.  Boston,  Mass. 

Proc.  and  Trans.  N.  S.  Inst.  Nat.  Sci. — Proceedings  and  Transactions  of 
the  Nova  Scotia  Institute  of  Natural  Science.  Halifax,  Nova  Scotia. 

Proc.  Bost.  Soc.  Nat.  Hist. — Proceedings  of  the  Boston  Society  of  Nat- 
ural History.  Boston,  Mass. 

Proc.  Colo.  Sci.  Soc.— Proceedings  of  .he  Colorado  Scientific  Society.  Den- 
ver, Colo. 

Raymond's  Reports. — Mineral  Resources  West  of  the  Rocky  Mountains- 
Washington,  1867-1876.  The  first  two  volumes  were  edited  by  J.  Ross- 
Browne,  the  others  by  R.  W.  Raymond. 


xvi  ABBREVIATIONS. 

Trans.  Min.  Asso.  and  Inst.,  Cormvall. — Transactions  of  the  Mining  As- 
sociation and  Institute  of  Cornwall.    Tuckingmill,  Camborn,  England. 
Trans.  N.  Y.  Acad.  of  Sci.—  Transactions  of  the  New  York  Academy  of 

Sciences,  formerly  the  Lyceum  of  Natural  History. 
Zeit.  d.  d.  g.  Ges. — Zeitschrift  der  deutschen  geologischen  Gesellschaft. 

Berlin,  Germany. 
Zeitsch.  f.  B.,  H.  und  S.  im  P.  St.— Zeitschrift  fur  Berg-,  Huetten-,  und 

Salinenwesen  im  Preussischen  Staat.  Berlin,  Germany. 
Zeitschr.  f.  Krys. — Zeitschrift  fur  Krystallographie.  Munich,  Germany. 
The  remaining  abbreviations  are  deemed  self-explanatory.  Tne  num- 
bering of  the  paragraphs  is  on  the  following  principle :  The  first  digit 
Tefers  invariably  to  the  part  of  the  book,  the  second  two  digits  to  the 
•chapter,  and  the  last  two  to  the  paragraph  of  the  chapter. 


PART  I. 

INTRODUCTORY. 


CHAPTER  I. 

GENERAL  GEOLOGICAL  FACTS  AND  PRINCIPLES. 

1.01.01.*  In  the  advance  of  geological  science  the  standpoints 
from  which  the  strata  forming  the  earth's  crust  are  regarded  neces- 
sarily change,  and  new  points  of  view  are  established.  In  the  last 
two  years  two  have  become  especially  prominent,  and  there  are 
now  two  sharply  contrasted  positions  from  which  to  obtain  a  con- 
ception of  the  structure  and  development  of  the  globe.  The  first 
is  the  physical,  the  second  the  biological.  We  may,  for  example, 
consider  the  surface  of  the  earth  as  formed  by  rocks,  differing  in 
one  part  and  another,  and  these  different  rocks  or  groups  of  rocks 
are  known  by  different  names.  The  names  have  no  special  refer- 
ence to  the  animal  remains  found  in  them,  but  merely  indicate  that 
series  of  related  strata  form  the  surface  in  particular  regions.  On 
the  other  hand,  the  rocks  are  also  regarded  as  having  been  formed 
in  historical  sequence,  and  as  containing  the  remains  of  organisms 
characteristic  of  the  period  of  their  formation.  They  illustrate  the 
development  of  animal  and  vegetable  life,  and  in  this  way  afford 
materials  for  historical-biological  study.  In  the  original  classifica- 
tion the  biological  and  historical  considerations  are  all-important. 
But  when  once  the  rocks  are  placed  in  their  true  position  in  the 
scale,  and  are  named,  these  considerations,  for  many  purposes,  no 
longer  concern  us.  The  formations  are  regarded  simply  as  mem- 
bers in  the  physical  constitution  of  the  outer  crust.  The  Interna- 
tional Geological  Congress  held  in  Berlin  in  1885  expressed  these 
different  points  of  view  in  two  parallel  and  equivalent  series  of 
geological  terms,  which  are  tabulated  on  p.  4.  They  are  now  very 


*  The  numbers  at  the  beginning  of  the  paragraphs  are  so  arranged 
that  the  first  figure  denotes  the  part  of  the  book,  the  next  two  figures 
the  chapter,  and  the  last  two  the  paragraph.  Thus  1.06.21  means  Part 
I.,  Chapter  VI.,  Paragraph  21  under  Chapter  VI. 


4  KEMPS   ORE  DEPOSITS. 

generally  adopted.     For  clearness  in  illustration,  the  equivalent 
terms  employed  by  Dana  are  appended. 


Biological  Terms. 

Physical  Terms. 

Dana's  Terms. 

Illustrations. 

Era. 

Group. 

Time. 

Paleozoic. 

Period. 

System. 

Age. 

Devonian. 

Epoch. 

Series. 

Period. 

Hamilton. 

Age. 

Stage. 

Epoch. 

Marcellus. 

The  United  States  Geological  Survey  divides  as  follows  :  Era 
and  System,  Period  and  Group,  Epoch  and  Formation.  In  consider- 
ing the  ore  deposits  of  the  country,  we  employ  only  the  physical 
terms.  We  understand,  of  course,  the  chronological  position 
of  the  systems  in  the  historical  sequence,  but  it  is  of  small  moment 
in  this  connection  what  may  be  the  forms  of  life  inclosed  in  them. 
The  purely  physical  character  of  the  rocks — whether  crystalline  or 
fragmental ;  whether  limestone,  sandstone,  granite,  or  schists ; 
whether  folded,  faulted,  or  undisturbed — are  the  features  on  which 
we  lay  especial  stress.  In  all  the  periods  the  same  sedimentary 
rocks  are  repeated,  and  in  the  hand  specimen  it  is  often  impossible 
to  distinguish  those  of  different  ages  from  one  another.  The 
classification,  briefly  summarized,  is  as  follows  : 

1.01.02.  ARCHAEAN  GROUP. — I.  Laurentian  System.  II.  Hu- 
ronian  System.  Additional  subdivisions  have  been  introduced  by 
Canadian  and  Minnesota^geologists  (Animikie,  Montalban,  etc.), 
and  there  is  a  tendency  to  group  all  the  later  schistose  members, 
especially  in  the  region  of  the  Great  Lakes,  under  the  name  Algon- 
kian.  (See  discussion  under  Example  9.) 

PALEOZOIC  GROUP. — III.  Keweenawan  System.  (This  may  be- 
long with  the  Archaean.)  IV.  Cambrian  System  :  (a)  Georgian 
Stage  ;  (b)  Acadian  Stage  ;  (c)  Potsdam  Stage.  V.  Lower  Silurian 
System.  (A)  Canadian  Series  :  (a)  Calciferous  Stage  ;  (b)  Chazy 
Stage.  (This  will  probably  experience  revision.)  (J?)  Trenton 
Series  :  (a)  Trenton  Stage  ;  (b)  Utica  Stage  ;  (c)  Cincinnati  or 
Hudson  River  Stage.  VI.  Upper  Silurian  System.  ( A)  Niagara 
Series  :  (a)  Medina  Stage  ;  (b)  Clinton  Stage  ;  (c)  Niagara  Stage. 
(J3)  Salina  Series.  (  C )  Lower  Helderberg  Series.  (D)  Oriskany 
Series.  (The  Oriskany  may  be  made  the  base  of  the  Devonian.) 
VII.  Devonian  System.  (^L)  Corniferous  Series  :  (a)  Cauda-Galli 
Stage  ;  (b)  Schoharie  Stage  ;  (c)  Corniferous  Stage.  (B)  Hamilton 
Series  :  (a)  Marcellus  Stage  ;  (b)  Hamilton  Stage  ;  (c)  Genesee 


* 

GENERAL   GEOLOGICAL  FACTS  AND  PRINCIPLES.          5 

Stage.  ( C )  Chemung  Series  :  (a)  Portage  Stage  ;  (b)  Chemung 
Stage.  (Z>)  Catskill  Series.  VIII.  Carboniferous  System.  (A) 
Subcarboniferous  or  Mississippian  Series.  (B)  Carboniferous 
Series.  (C)  Permian  Series. 

MESOZOIC  GROUP. — IX.  Triassic  System.  X.  Jurassic  System. 
IX.  and  X.  are  not  sharply  divided  in  the  United  States,  and  we 
often  speak  of  Jura-Trias.  A  stratum  of  gravel  and  sand,  along 
the  Atlantic  coast,  that  contains  Jurassic  fossils  has  been  called 
the  Potomac  formation  by  McGee.  XL  Cretaceous  System.  Sub- 
divisions differ  in  different  parts  of  the  country.  Atlantic  Border  : 
(a)  Raritan  Stage  ;  (b)  New  Jersey  Greensand  Stage.  Gulf  States  : 

(a)  Tuscaloosa  Stage  ;    (b)   Eutaw  Stage  ;    (c)  Rotten  Limestone 
Stage  ;    (d)   Ripley  Stage.      Rocky    Mountains  :     (a)    Comanche 
Stage  ;  (b)  Dakota  Stage  ;  (c)  Benton  Stage  ;  (d)  Niobrara  Stage  ; 
(e)  Pierre  Stage  ;  (/)  Fox  Hills  Stage  ;  (g)  Laramie  Stage.    Stages 
(c),  (d),  (e),  and  (/)  are  sometimes  collectively  called  the  Colorado 
Stage.      Pacific  coast  :    (a)   Shasta  Stage  ;    (b)  Chico  Stage  ;    (c) 
Tejon  Stage. 

CENOZOIC  GROUP. — XII.  Tertiary  System.  (A)  Eocene  or 
Alabama  Series  :  Gulf  States,  (a)  Claiborne  Stage  ;  (b)  Jackson 
Stage  ;  (c)  Vicksburg  Stage.  Western  States,  (a)  Puerco  Stage  ; 

(b)  Wasatch  Stage  ;    (c)  Wind  River  Stage  ;    (d)  Bridger  Stage  ; 
(e)  Uintah  Stage.     (13)   Miocene  or  Yorfctown  Series,   including 
perhaps  the  Sumter  of  the  Atlantic  Border.     On  the  Pacific  Slope 
it  has  the  following  :  (a)  White  River  Stige  ;  (b)  John  Day  Stage  ; 

(c)  Loup  Fork  Stage.     (  C)  Pliocene  Series.     (Of  doubtful  Ameri- 
can determination.)       XIII.   Quaternary   System.       (A)    Glacial 
Series.     (B)  Champlain  Series.     (  C)  Terrace  Series.     (D)  Recent 
Series.     Pleistocene  is  sometimes  employed  as  a  name  for  the  early 
Quaternary,  especially  south  of  the  Glacial  Drift.     The  Quaternary 
granitic  sands  and  clay  of  the  coast  below  the  terminal  moraine  have 
been  called  by  McGee  the  Appomattox  and  Columbia  formations. 

Other  terms  are  also  often  used,  especially  when  we  do  not  wish 
to  speak  too  definitely.  "  Formation  "  is  a  word  loosely  employed 
for  any  of  the  above  divisions.  "Terrane"  is  used  much  in  the 
same  way,  but  is  rather  more  restricted  to  the  lesser  divisions.  A 
stratum  is  one  of  the  larger  sheet-like  masses  of  sedimentary  rock 
of  the  same  kind;  a  bed  is  a  thinner  subdivision  of  a  stratum. 
"  Horizon  "  serves  to  indicate  a  particular  position  in  the  geologi- 
cal column  ;  thus,  speaking  of  the  Marcellus  Stage,  we  say  that 
shales  of  this  horizon  occur  in  central  New  York. 


6  KEMP'S   ORE  DEPOSITS. 

1.01.03.  The  rock  species  themselves  are  classified  into  three 
great  groups — the    Igneous,  the  Sedimentary,  and  the  Metamor- 
phic. 

The  Igneous  (synonymous  terms,  in  whole  or  in  part:  mas- 
sive, eruptive,  volcanic,  plutonic)  include  all  those  which  have  so- 
lidified from  a  state  of  fusion.  They  are  marked  by  three  types 
of  structure — the  holo-crystalline,  the  porphyritic,  and  the  glassy, 
depending  on  the  circumstances  under  which  they  have  cooled. 
Under  the  first  type  of  structure  come  the  granites,  syenites,  dio- 
rites,  gabbros,  diabases,  and  peridotites;  under  the  second,  quartz- 
porphyries,  rhyolites,  porphyries,  trachytes,  porphyrites,  andesites, 
and  basalt;  under  the  third,  pitchstone,  obsidian,  and  other  glasses. 

The  Sedimentary  rocks  are  those  which  have  been  deposited  in 
water.  They  consist  chiefly  of  the  fragments  of  pre-existing  rocks 
and  the  remains  of  organisms.  They  include  gravel,  conglom- 
erate, breccia,  sandstone, — both  argillaceous  and  calcareous, —  shales, 
clay,  limestone,  and  coal.  In  volcanic  districts,  and  especially 
where  the  eruptions  have  been  submarine,  extensive  deposits  of 
volcanic lapilli  and  fine  ejectments  have  been  formed,  called  tuffs. 
With  the  sedimentary  rocks  we  place  a  few  that  have  originated 
by  the  evaporation  of  solutions,  such  as  rock  salt,  gypsum,  etc. 

The  Metamorphic  rocks  are  usually  altered  and  crystallized 
members  of  the  sedimentary  series,  but  igneous  rocks  are  known  to 
be  Subject  to  like  change,  especially  when  in  the  form  of  tuffs. 
They  are  all  more  or  less  Crystalline,  more  or  less  distinctly  bedded 
or  laminated,  of  ancient  geological  age  or  in  disturbed  districts. 
They  include  gneiss,  crystalline  schists,  quartzite,  slate,  marble,  and 
serpentine. 

After  a  brief  topographical  survey,  we  shall  employ  the  above 
terms  to  summarize  the  geological  structure  of  the  United  States. 
The  several  purely  artificial  territorial  divisions  are  made  simply 
for  convenience.  Nothing  but  intelligent  travel  will  perfectly  ac- 
quaint one  with  the  topographical  and  geological  structure  of  the 
country,  and  in  this  connection  Macfarlane's  "  Geological  Railway 
Guide"  and  a  geological  map  are  indispensable. 

1.01.04.  On  the  east  we  note  the  great  chain  of  the  Appalachi- 
ans, with  a  more  or  less  strongly  marked  plain  between  it  and  the 
sea.     This  is  especially  developed  in  the  south,  and  is  now  generally 
called  the  Coastal  Plain.     It  is  of  late  geological  age  and  contains 
the  pine  barrens  and  seacoast  swamps.     The  Appalachians  them- 
selves consist  of  many  ridges,  running  on  the  north  into  the  White 


GENERAL    GEOLOGICAL   FACTS  AND  PRINCIPLES.          7 

Mountains,  the  Green  Mountains,  and  the  Adirondacks.  Farther 
south  the  Highlands  of  New  York  and  New  Jersey,  the  South 
Mountain  of  Pennsylvania,  the  Alleghanies,  the  Blue  Ridge,  and 
the  other  southern  ranges  make  up  the  great  eastern  continen- 
tal mountain  system.  In  western  New  York  and  Ohio  we  find  a 
rolling,  hilly  country;  in  Kentucky  and  Tennessee,  elevated  table- 
land, with  deeply  worn  river  valleys.  Indiana,  Illinois,  Iowa,  and 
Missouri  contain  prairie  and  rolling  country,  more  broken  in  southern 
Missouri  by  the  Ozark  uplift.  In  Michigan,  Wisconsin,  and  Minne- 
sota the  surface  is  rolling  and  hilly  with  numerous  lakes.  In  Ar- 
kansas, Louisiana,  and  Mississippi  there  are  bottom  lands  along  the 
Mississippi  and  Gulf,  with  low  hills  back  in  the  interior.  Across 
Arkansas  and  Indian  Territory  runs  the  east  and  west  Ouachita 
uplift.  West  of  these  States  comes  the  great  billowy  prairie  region, 
and  then  the  chain  of  the  Rocky  Mountains,  consisting  of  high, 
dome-shaped  peaks  and  ridges,  with  extended  elevated  valleys 
(the  parks)  between  the  ranges.  Some  distance  east  of  the  main 
chain  are  the  Black  Hills,  made  up  of  later  concentric  formations 
around  a  central,  older  nucleus,  and  also  the  extinct  volcanic  dis- 
trict of  the  Yellowstone  National  Park.  In  western  Colorado,  Utah, 
and  New  Mexico,  between  the  Rocky  Mountains  and  the  Wasatch, 
is  the  Colorado  plateau,  an  elevated  tableland.  This  is  terminated  by 
the  north  and  south  Wasatch  range  and  is  traversed  east  and  west 
by  the  Uintah  range.  West  of  this  lies  the  region  called  the  Great 
Basin,  characterized  by  alkaline  deserts,  and  subordinate  north 
and  south  ranges  of  mountains.  Next  comes  the  chain  of  the  Sier- 
ra Nevada,  and  lying  between  it  and  the  Coast  range  is  the  great 
north  and  south  valley  of  California.  This  rises  in  the  compara- 
tively low  Coast  range,  which  slopes  down  to  the  Pacific  Ocean. 
To  the  north,  these  mountains  extend  into  eastern  Oregon  and 
Washington,  with  forests  and  fertile  river  valleys.  These  topograph- 
ical features  are  important  in  connection  with  what  follows,  for  the 
reason  that  the  ore  deposits  especially  favor  mountainous  regions. 
Mountains  themselves  are  due  to  geological  disturbances — upheav- 
al, folding,  faulting,  etc. — and  are  often  accompanied  by  great  ig- 
neous outbreaks.  They  therefore  form  the  topographical  surround- 
ings most  favorable  to  the  development  of  cavities,  waterways, 
and  those  subterranean,  mineral-bearing  circulations  which  would 
fill  the  cavities  or  replace  the  rock  with  useful  minerals. 

1.01.05.    GEOLOGICAL  OUTLINE.    I.     New  England,  New  York, 
Neio  Jersey,  and  Eastern  Pennsylvania  District. — In  New  Eng- 


8  KEMP'S  ORE  DEPOSITS. 

land  and  northern  New  York  the  Archaean  is  especially  devel- 
oped, forming  the  White  Mountains,  the  Adirondacks,  and  the 
Highlands  of  New  York  and  New  Jersey.  These  all  consist  of 
granite  and  other  igneous  rock,  of  gneiss,  and  of  crystalline  schists. 
There  are  also  great  areas  of  metamorphic  rocks  whose  true  age 
may  be  later.  The  Green  Mountains  are  formed  of  such,  and  were 
elevated  at  the  close  of  the  Lower  Silurian.  In  New  England  there 
are  small,  scattered  exposures  of  the  undoubted  Paleozoic  (Devo- 
nian, Carboniferous).  In  eastern  New  York,  and  to  some  extent  in 
New  Jersey  and  eastern  Pennsylvania,  the  entire  Paleozoic,  except 
the  Carboniferous,  is  strongly  developed.  Up  and  down  the  coast 
there  are  narrow  north  and  south  estuary  deposits  of  red  Jura-Tri- 
as sandstone,  which  are  pierced  by  diabase  eruptions.  The  Creta- 
ceous clays  are  strong,  and  Tertiary  strata  occur  at  Martha's  Vine- 
yard, in  Massachusetts,  while  over  all  as  far  south  as  Trenton  is 
found  the  glacial  drift.  Between  the  Archaean  ridges  of  the  High- 
lands and  the  first  foldings  of  the  Paleozoic  on  the  west  is  found 
the  so-called  Great  Valley,  which  also  runs  to  the  south  and  is  a 
very  important  topographic  and  geologic  feature.  It  follows  the 
outcrop  of  the  Siluro-Cambrian  limestones,  to  whose  erosion  it  is  due. 

II.  Eastern- Middle   and  Southeastern    Coast    District. — The 
low  plains  of  the  coast  are  formed  by  Quaternary,  Tertiary,  and 
Cretaceous,  consisting  of  gravel,  sand,  shell  beds,  and  clay.     In- 
land there  are  exposures  of  Jura-Trias,  as  in  the  north.     The  Ar- 
chaean crystalline  rocks  are  also  seen  at  numerous  points  not  far 
from  the  ocean.     Florida  is  largely  made  up  of  limestones,  with  a 
mantle  of  calcareous  sand. 

III.  Alleghany  Region   and   the   Central  Plateau. — The  Ap- 
palachian  mountain   system,    from   New  York  to  Alabama,  con- 
sists principally  of  folded  Paleozoic  (largely  Carboniferous),  with 
Archaean  ridges  on  its  eastern  flank.     There  is  an  enormous  devel- 
opment of  folds,  with  northeast  and  southwest  axes.     On  the  west 
they  are  succeeded  by  the  plateau  region  of  Kentucky  and  Tennes- 
see, chiefly  Paleozoic.     Along  central  latitudes  the  Archaean  does 
not  again  appear  east  of  the  Mississippi. 

IV.  Region  of  the  Great  Lakes. — In  Michigan,  Wisconsin,  and 
Minnesota  the  Archaean   rocks   are   extensively  developed,    both 
Laurentian  and  Huronian.     Around  Lake  Superior  are  found  the 
igneous  and  sedimentary  rocks  of  the  Keweenawan,  followed  by 
the  lower  Paleozoic.     Lake  Michigan  and  Lake  Huron  are  sur- 
rounded by  Silurian,  Devonian,  and  Carboniferous;  Lake  Erie,  by 


GENERAL   GEOLOGICAL  FACTS  AND  PRINCIPLES.          9 

Devonian  ;  Lake  Ontario,  by  Silurian.  Running  -south  through 
Ohio,  we  find  an  important  fold  known  as  the  Cincinnati  uplift, 
with  a  north  and  south  axis.  It  was  elevated  at  the  close  of  the 
Lower  Silurian.  In  the  lower  peninsula  of  Michigan  and  in  eastern 
Ohio  and  western  Pennsylvania  the  Carboniferous  is  extensively 
developed. 

V.  Mississippi  Valley. — The  head    waters  of  the    Mississippi 
are  in  the  Archaean.      It  then  passes  over  Cambrian  and  Siluiian 
strata  in  Minnesota,  Wisconsin,  northern  Iowa,  and  Illinois,  which 
in  these  States  lie   on  the  flanks  of   the   Archaean    "  Wisconsin 
Island"  of  central  Wisconsin.     These  are  succeeded  by  subordi- 
nate Devonian,  and  in  southern  Iowa,  Illinois,  and  Missouri  by  Car- 
boniferous.    In  southern  Missouri  the  Lower  Silurian  forms  the 
west  bank.     Thence  to  the  Gulf  the  river  flows  on  estuary  deposits 
of  Quaternary  age,  with  Tertiary  and  Cretaceous  farther  inland. 

VI.  Gulf  Region. — The  Gulf  States  along  the  water  front  are 
formed  by  the  Quaternary.     This  is  soon  succeeded  inland  by  very 
extensive  Tertiary  beds,  which  are  the  principal  formation   repre- 
sented. 

VII.  Prairie  Region. — West  of   the  Paleozoic  rocks  of  the 
States  bordering  on  the  Mississippi  is  found  a  great  strip  of  Creta- 
ceous running  from    the  Gulf   of  Mexico  to  and  across  British 
America,  and  bounded  on  the  west  by  the  foothills  of  the  Rocky 
Mountains.     A  few  Tertiary  lake  deposits  are  found  in  it.     Quite 
extensive  Triassic  rocks  are  developed  on  the  south.     The  surface 
is  a  gradually  rising  plateau  to  the  Rocky  Mountains. 

VIII.  Region  of  the  Rocky  Mountains,  the  Black  Hill§9  and 
the  Yellowstone  National  Park. — The  Rocky  Mountains  rise  from 
the  prairies  in  long  north  and  south  ranges,  consisting  of  Archaean 
axes  with  the  Paleozoic  in  relatively  small  amount,  but  with  abun- 
dant Mesozoic  on  the  east  and  west  flanks.     In  the  parks  are  found 
lake  deposits  of  Tertiary  age.     There  are  also  great  bodies  of  igne- 
ous rocks,  which  attended    the  various  upheavals.     The  principal 
upheavals  began  at  the  close  of  the  Cretaceous.     The  outlying 
Black  Hills  consist  of  an  elliptical  Archaean  core,  with  concentric 
Paleozoic  and  Mesozoic  strata  laid  up  around  it.     The  National 
Park   consists  chiefly   of  igneous    (volcanic)    rocks    in    enormous 
development. 

IX.  Colorado  Plateau. — The  Rocky  Mountains  shade  out  on 
the  west  into  a  great  elevated  plateau,  extending  to  central  Utah, 
where  it  is  cut  off  by  the  north  and  south  chain  of  the  Wasatch. 


10  KEMP'S  ORE  DEPOSITS. 

The  Uintah  fountains  are  an  east  and  west  chain  in  its  northern 
portion.  The  rocks  on  the  north  are  chiefly  Tertiary,  with  Meso- 
zoic  and  Paleozoic  in  the  mountains.  To  the  south  are  found 
Cretaceous  and  Triassic  strata,  with  igneous  rocks  of  great  extent. 
The  principal  upheaval  of  the  Wasatch  began  at  the  close  of  the 
Carboniferous  and  seems  still  to  be  in  progress. 

X.  Region  of  the  Great  Basin. — Between  the  Wasatch  and 
the  Sierra  Nevada  ranges  is  found  the  Great  Basin  region,  once 
lake  bottoms,  now  very  largely  alkaline  plains  of  Quaternary  age. 
The  surface  is  diversified  by  subordinate  north  and  south  ranges, 
formed  by  great  outflows  of  eruptive  rocks,  and  by  tilted  Paleozoic. 
The  ranges  are  extensively  broken  and  the  stratified  rocks  often 
lie  in  confused  and  irregular  positions.  There  is  no  drainage  to 
the  ocean. 

XL  Region  of  the  Pacific  Slope. — The  depression  of  the  Great 
Basin  is  succeeded  by  the  heights  of  the  Sierra  Nevada.  On  the 
west  the  Sierras  slope  down  into  the  Central  Valley  of  California. 
The  flanks  are  largely  metamorphosed  Jurassic  and  Cretaceous 
rocks  with  great  developments  of  igneous  outflows.  The  surface 
rises  again  in  the  Coast  ranges,  which  slope  away  farther  west  to 
the  ocean.  In  addition  to  the  Jurassic  and  Cretaceous,  the  Tertiary 
and  Quaternary  are  also  developed,  and  in  the  Coast  ranges  are 
many  outflows  of  igneous  rock.  The  principal  upheaval  of  the 
Sierra  Nevada  began  at  the  close  of  the  Jurassic,  that  of  the  Coast 
range  at  the  close  of  the  Miocene  Tertiary. 

XII.  Region  of  the  Northwest. — Washington  and  Oregon, 
along  the  coast,  are  formed  by  Cretaceous  and  Tertiary  strata 
similar  to  California.  But  inland,  immense  outpourings  of  igneous 
rocks  cover  the  greater  portion  of  both  States  and  extend  into 
Idaho.  On  the  north  the  Carboniferous  is  extensive,  running  east- 
ward into  Montana.  Quaternary  and  Tertiary  lake  deposits  are 
also  not  lacking. 

1.01.06.  On  the  Forms  Assumed  by  Rock  Masses. — All  sedimen- 
tary rocks  have  been  originally  deposited  in  beds,  approximately 
horizontal.  They  are  not  of  necessity  absolutely  horizontal,  be- 
cause they  may  have  been  formed  on  a  sloping  bottom  or  in  a  delta, 
in  both  of  which  cases  an  apparent  dip  ensues.  We  find  them 
now,  however,  in  almost  all  cases  changed  from  a  horizontal  posi- 
tion by  movements  caused  primarily  by  the  compressive  strain  in 
the  earth's  crust.  Beds  thus  assume  folds  known  as  monoclines, 
anticlines,  and  synclines. 


GENERAL   GEOLOGICAL  FACTS  AND  PRINCIPLES.       U 

A  monocline  is  a  terrace-like  dropping  of  a  bed  without  changing 
the  direction  of  the  dip.  There  is  usually  a  zone,  more  or  less 
shattered,  along  the  folded  portion,  and  such  a  zone  may  become 
a  storage  receptacle.  Monoclines  of  a  gentle  character  in  Ohio, 
which  have  been  detected  by  Orton  in  studies  of  natural  gas,  have 
been  called  "arrested  anticlines."  An  anticline  is  a  convex  fold 
with  opposing  dips  on  its  sides,  while  a  syncline  is  a  concave  fold 
with  the  dips  on  its  sides  coming  together.  We  speak  of  the  axis 
of  a  fold,  and  this  marks  the  general  direction  of  the  crest  or 
trough.  The  axis  is  seldom  straight  for  any  great  distance.  Folds 
are  often  broken  and  faulted  across  the  strike  of  their  axes,  and 
this  causes  what  is  called  a  "pitch  "of  the  axes  and  makes  the 
original  dips  run  diagonally  down  on  the  final  one.  Folds  are  the 
primary  cause  of  the  phenomena  of  dip  and  strike.  Horizontal 
beds  have  neither.  A  dome-like  elevation  of  beds,  with  dips  radi- 
ating in  every  direction  from  its  summit,  is  called  a  quaquaversal, 
but  it  is  a  rare  thing.  An  anticline  or  syncline  writh  equal  dips  on 
opposite  sides  of  its  axes  is  called  a  normal  fold.  If  the  dip  is 
steeper  on  one  side  than  on  the  other,  it  is  an  overthrown  fold  ;  if 
the  sides  are  crushed  together,  it  is  a  collapsed  or  sigmoid  fold. 

Igneous  rocks  are  in  the  form  of  sheets  (the  term  "bed"  should 
be  restricted  to  sedimentary  rocks),  knobs  or  bosses,  necks,  lacco- 
lites,  and  dikes.  A  sheet  is  the  form  naturally  assumed  by  surface 
flows,  and  by  an  igneous  mass  which  has  been  intruded  between 
beds.  It  has  relatively  great-length  and  breadth  as  compared  with 
its  thickness,  and  coincides  with  its  walls  in  dip  and  strike.  A 
knob,  or  boss,  is  an  irregular  mass,  of  approximately  equal  length 
and  breadth,  which  may  be  related  in  any  way  to  the  position  of 
its  walls.  Such  masses  are  often  left  projecting  by  erosion.  A 
neck  is  the  filled  conduit  of  a  volcano,  which  sometimes  remains 
after  the  overlying  material  has  been  denuded.  A  laccolite  is  a 
lenticular  sheet  which  has  spread  between  beds  radially  from 
its  conduit,  and  thus  has  never  reached  the  surface,  unless  re- 
vealed by  subsequent  erosion.  A  dike  is  a  relatively  long  and 
narrow  body  of  igneous  rock  which  has  been  intruded  in  a  fissure. 
It  is  analogous  to  a  vein,  but  the  term  "  vein  "  ought  not  to  be  ap- 
plied to  an  undoubtedly  igneous  rock.  Some  granitic  mixtures, 
however,  of  quartz,  feldspar,  and  mica,  leave  us  yet  in  uncertainty 
as  to  whether  they  are  dikes  or  veins.  (See  Example  56.)  From 
the  above  it  will  be  seen  at  once  that  bosses,  knobs,  and  necks  may 
be  practically  indistinguishable. 


CHAPTER  II. 


ON  THE   FORMATION  OF  CAVITIES  IN  ROCKS. 


1.02.01.  By  Local  Contraction. — In  the  contraction  caused 
by  cooling,  drying,  or  hardening,  both  igneous  and  sedimentary 
rocks  break  into  more  or  less  regular  masses  along  division  planes, 
called  joints,  or  diaclases.  Numerous  cracks  and  small  cavities  are 
thus  formed.  Basaltic  columns,  or  the  prismatic  masses,  formed 
by  the  separation,  in  cooling  and  consolidating,  of  the  heavier  basic 
rocks,  along  planes  normal  to  the  cooling  surface,  are  good  illustra- 
tions of  the  first.  Larger  manifestations  of  them  often  become 
filled  with  zeolites,  calcite,  and  other  secondary  minerals.  Granitic 


FIG.  1. — Illustration  of  rifting  in  granite  at  Cape  Ann,  Mass. 
After  R.  S.  Tarr. 

rocks  and  porphyries  break  up  less  regularly  from  the  same  cause, 
but  still  exhibit  prismoids  and  polygonal  blocks  and  benches.  (J. 
P.  Iddings'  paper  on  "The  Columnar  Structure  in  the  Igneous 
Rocks  on  Orange  Mountain,  N.  J.,"  Amer.  Joitr.  Sci.,  III.,  xxxi. 
320,  is  an  excellent  discussion.)  Large  cracks  have  been  referred 
to  this  cause,  which  have  afterward  formed  important  receptacles 
for  ores.  (See  Example  11  a.)  Very  small  microscopic  cracks  may 
occasion  lines  of  weakness  and  brecciation  which  are  not  readily 
apparent.  They  afford  a  cleavage,  called  rifting,  but  are  not  well 
understood.  (See  R.  S.  Tarr,  "  On  Rifting  in  Cape  Ann  Granites," 
Amer.  Jour.  Sci.,  April,  1891.)  Joints  are  generally  prominent  in 


L1RR4 

ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  13 

sedimentary  rocks,  and  probably  afford  many  of  the  regular  planes 
of  separation  which  are  often  seen  crossing  one  or  several  beds. 
They  are  chiefly  due  to  drying  and  consolidation.  Both  the  joints 
formed  by  cooling  and  those  formed  by  drying  may  be  afterward 
modified  or  increased  by  rock  movements,  so  that  it  may  be  a 
matter  of  difficulty  to  decide  between  the  two  forms  of  origin. 
The  undulatory  tremors  of  an  earthquake  have  been  cited,  with 
great  reason,  by  W.  O.  Crosby  as  a  prolific  cause  of  joints.* 

1.02.02.  Cavities  Formed  by  More  Extensive  Movements  in 
the  Earth* s  Crust. — The  strains  induced  by  the  compression  in  the 
outer  portion  of  the  earth  are  by  far  the  most  important  causes  of 
fractures.  The  compression  develops  a  tangential  stress  which  is 
resisted  by  the  archlike  disposition  of  the  crust.  (By  the  term 
"  crust "  is  simply  meant  the  outer  portion  of  the  globe  without 
reference  to  the  character  of  the  interior.)  Where  there  is  insuf- 
ficient support,  gravity  causes  a  sagging  of  the  material  into  syn- 
clinals, which  leave  salient  anticlinals  between  them.  Where  the 
tangential  strain  is  also  greater  than  the  ability  of  the  rocks  to 
resist,  they  are  upset  and  crumpled  into  folds  from  the  thrust. 
Both  kind  of  folds  are  fruitful  causes  of  fissures,  cracks,  and 
general  shattering,  and  every  slip  from  yielding  sends  its  oscilla- 
tions abroad,  which  cause  breaks  along  all  lines  of  weakness.  The 
simplest  result,  either  from  sagging  or  from  thrust,  is  a  fissure,  on 
one  of  whose  sides  the  Avail  has  dropped,  or  on  the  other  of  which 
it  has  risen,  or  both,  as  will  be  more  fully  described  under  "  Faults." 
If  the  rocks  are  firm  and  quite  thickly  bedded,  as  is  the  case  with 
limestones  and  quartzites,  the  separation  is  cleanly  cut ;  but  if 
they  are  softer  and  more  yielding,  they  are  sheared  downward  on 
the  stationary  or  lifting  side,  and  upward  on  the  one  which  rela- 
tively sinks.  Such  fissures  may  pass  into  folds  along  their  strike, 
as  at  Leadville,  Colo. 


*  In  addition  to  the  usual  text-books  the  following  references  may  be 
consulted  :  W.  O.  Crosby,  "  On  the  Origin  of  Jointed  Structures,"  Boston 
Soc.  Nat.  Hist.,  XXII.,  October,  1882,  p.  72;  Amer.  Jour.  Sci.,  III.,  xxv. 
476  ;  G.  K.  Gilbert,  "  On  the  Origin  of  Jointed  Structures,"  Amer.  Jour.  Sci., 
III.,  xxiv.  50,  and  xxvii.  47;  J.  H.  Kinahan,  Valleys,  and  their  Relations 
to  Fissures,  Fractures,  and  Faults,  London,  Triibner  &  Co.  See  also  a 
short  letter  in  the  Amer.  Jour.  Sci.,  III.,  xxiv.,  p.  68,  on  the  "  Origin  of 
Jointed  Structures;"  J.  Leconte,  "Origin  of  Jointed  Structure  in  Undis- 
turbed Clay  and  Marl  Deposits,"  Amer.  Jour.  Sci.,  III.,  xxiii.  233 ;  W.  J. 
McGee,  "  On  Jointed  Structure,"  Amer.  Jour.  Sci.,  III.,  xxv.  152,  476. 


14  KEMP'S   ORE  DEPOSITS. 

1.02.03.  A  phenomenon  which  is  especially  well  recognized  in 
metamorphic  regions,  and  which  is  analogous  to  those  last  cited, 
is  furnished  by  the  so-called  "  shear  zones."     A  faulting   move- 
ment, or  a  crush,  may  be  made  apparent  by  changes  in  mineralogi- 
cal  composition  and  structure.      Massive  diabases,  for  instance, 
pass  into  hornblende-schists  or  amphibolites  for  limited  stretches. 
Garnets  and  other   characteristically  metamorphic    minerals    ap- 
pear, and  pyroxenes  alter  to  amphiboles.    Strains  are  manifested  in 
the  optical  behavior  of  the  minerals  in  thin  sections  of  specimens 
taken  from  such  localities.     These   crushed  strips,  or  shear  zones, 
may  be  formed  with  very  slight  displacement,   but  they  afford 
favorable  surroundings  for  the  formation  of  ore  bodies.     This  con- 
ception of  the  original  condition  of  a  line  of  ore  deposition  is  a 
growing  favorite  with  recent  wrriters,  and  combined  with  the  idea 
of   replacement   is   often  applicable.      (See   Example    IV,    Butte, 
Mont.)     Fahlbands,  which  are  very  puzzling  problems,  may  have 
originated  as  shear  zones. 

1.02.04.  A  more  extended  effect  is  produced  by  the  mono- 
cline, which  has  a  double  line  of  shattered  rock  marking  both  the 
crest  and  the  foot  of  its  terrace.     Anticlines  and  synclines  occasion 
the  greatest  disturbances.     Comparatively  brittle  materials  like 
rocks  cannot  endure  bending  without  suffering  extended  fractures. 
When  strained  beyond  their  limit  of  resistance,  along  the  crest  of 
an  anticline  and  in  the  trough  of  a  syncline,  cracks  and  fractures 
are  formed  which  radiate  from  the  axis  of  each  fold.     As  these 
open  upward  and  outward  in  anticlines,  they  become  the  easiest 
points  of  attack  for  erosion,  so  that  it  is  a  very  common  thing  to  find 
a  stream  flowing  in  a  gorge,  which  marks  the  crest  of  an  anticline, 
while  synclinal  basins  are  frequently  left  to  form  the  summits  of 
ridges,  as  is  so  markedly  the  case  in  the  semi-bituminous  coal  basins 
of  Pennsylvania.     It  is  quite  probable,  however,  that  the  anticline 
may  have  been  leveled  off  at  this  fissured  crest  because  it  was  up- 
heaved under  water  and  became  exposed  at  its  vulnerable  summit 
to  wave  action. 

Ore  deposits  may  collect  in  these  fissured  strips,  of  which  the 
lead  and  zinc  mines  of  the  upper  Mississippi  Valley  (Example  24) 
are  illustrations.  Such  fissures  are  peculiar  in  that  they  exhibit  no 
displacement.  The  accompanying  figure  is  from  a  photograph  of 
a  ^gaping  crack  in  the  Aubrey  (Upper  Carboniferous)  limestone, 
twenty-five  miles  north  of  Caflon  Diablo  station,  Ariz.,  on  the  At- 
lantic and  Pacific  Railroad.  It  was  caused  by  a  low  anticlinal 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  15 

roll,  and  contained  water  about  one  hundred  feet  below  the  top. 
Its  reproduction  of  the  conditions  of  a  vein,  with  horse,  pinches 
and  swells,  devious  course,  and  all,  is  striking.  The  photograph 
was  made  by  Mr.  G.  K.  Gilbert,  of  the  United  States  Geological 
Survey,  and  to  his  courtesy  its  use  is  due. 


FIG.  2.— Open  fissure  in  the  Aubrey  limestone  (Upper  Carboniferous),  25 

miles  north  of  Canon  Diablo  station,  Ariz.,  on  the  A.  &  P.  R.  R. 

Photographed  by  G.  K.  Gilbert,  1»92. 

While  it  is  true  that  in  many  regions  the  folds  and  fractures 
have  resulted  in  this  simple  way,  and  exhibit  the  unmistakable 
course  through  which  they  have  passed,  yet  geological  structure 
is  by  no  means  always  so  clear.  Extended  disturbances,  great 
faults  and  displacements,  combined  with  folds  and  the  intrusion  of 


16  KEMP'S   ORE  DEPOSITS. 

igneous  rocks,  have  often  so  broken  up  a  district  that  it  is  a  matter 
of  much  difficulty  to  trace  out  the  course  through  which  it  has 
passed.  Subsequent  erosion,  or  the  superposition  of  heavy  beds  of 
gravel  or  forest  growths,  etc.,  may  so  obstruct  observation  even  of 
the  facts  as  to  add  to  the  obscurity.  The  expense  of  making  and  the 
consequent  scarcity  of  accurate  contour  maps  to  assist  in  such 
work  are  other  obstacles.  The  profound  dynamic  effects  wrought 
by  mountain-making  processes,  although  in  individual  cases  pro- 
ducing only  the  simpler  phenomena  already  cited,  yet  in  general 
are  much  more  extensive,  and  must  be  considered  in  the  study  of 
many  large  districts.  When  folds  are  the  result  of  compression  or 
thrust,  the  dynamic  effects  are  more  marked  than  in  those  formed 
by  sagging.  Faults  are  larger  and  more  abundant.  When  sedi- 
mentary beds  have  been  laid  down  along  an  older  axis  of  granite 
or  some  equally  resistant  rock  and  the  thrust  crowds  the  beds 
against  this  axis,  the  conditions  are  eminently  favorable  to  great 
fracturing  and  disturbance.  The  flanks  of  the  Rocky  Mountains 
furnish  such  examples. 

1.02.05.  There  are  also  great  lines  of  weakness  in  the  outer 
portion  of  the  earth,  which  seems  to  have  been  the  scene  of  fault- 
ing movements  from  a  very  early  period.     Thus  on  the  western 
front  of  the  Wasatch  Mountains,  in  Utah,  is  a  great  line  of  weak- 
ness,  that   was  first   faulted,  as    nearly   as  we   can    discover,    in 
Archaean  times,  and  has  suffered  disturbances  even  down  to  the 
present.      A  few  instances  of  actual  movements   within    recent 
years  have  been  recorded.     In  1889  a  sudden  small  fold  and  fissure 
developed  under  a  paper  mill  near  Appleton,  Wis.,  and  heaved  the 
building  four  and  a  half  inches.      (See  F.  Cramer,  "Recent  Rock 
Flexure,"  Amer.  Jour.   Sci.,  III.,.xxxix.  220.)     This  occurred  in 
what  was  regarded  a  settled  region  and  one  not  liable  to  disturb- 
ance. 

1.02.06.  Wherever  igneous   rocks   form  relatively  large  por- 
tions of  the  globe  they  necessarily  share  extensively  in  terrestrial 
disturbances.      Not  being  often  in  sufficiently  thin  sheets,  they 
rarely  furnish  the  phenomena  of  dip  and  strike.     Folds  are  largely 
wanting.      They  are  replaced  by  faults  and  shattering.      The  fis- 
sures thus  formed  are  at  times  of  great  size  and  indicate  impor- 
tant movements.     The  Comstock  Lode  fissure  is  four  miles  long 
and  in  the  central  part  exhibits  a  vertical  displacement  of  three 
thousand  feet.     (See  2. 1 1.  ]  9.)     Such  fissures  seldom  occur  alone,  but 
minor  ones  are  found  on  each  side  and  parallel  with  the  main  one. 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS. 


17 


1.02.07.  The  intrusion  of  igneous  dikes  may  start  earthquake 
vibrations  which  fracture  the  firm  rock  masses.  Fissures  caused 
in  this  way  radiate  from  the  center  of  disturbance  or  else  appear 
in  concentric  rings.  The  violent  shakings  which  so  often  attend 
great  volcanic  eruptions,  and  the  sinking  of  the  surface  from  the 
removal  of  underlying  molten  material,  all  tend  to  form  cracks 


FIG.  3.— Normal  fault  at  Leadville,  Colo.     After  A.  A.  Blow. 

and  cavities.  They  are  possible  causes  which  may  well  be  borne 
in  mind  in  the  study  of  an  igneous  district. 

1.02.08.  Faults. — When  fractures  have  been  formed  by  any  of 
the  means  referred  to  above,  and  the  opposite  walls  slip  past  each 
other,  so  as  not  to  correspond  exactly  at  all  horizons,  they  are 
called  "faults,"  a  term  which  indicates  this  lack  of  correspondence. 

The  separation  is  chiefly  due  to  the  relative  slipping  down  or  sink- 
ing of  one  side.  The  distance  through  which  this  has  taken  place 
is  called  the  amount  of  displacement,  or  throw.  Faults  are  most 
commonly  inclined  to  the  horizon,  so  that  there  is  both  a  vertical 
and  a  horizontal  displacement.  What  would  be  the  dip  of  an  in- 
clined stratum  is  in  a  fault  now  generally. known  as  the  "hade," 
although  the  word  formerly  had  a  different  meaning.  Experience 
has  shown  that  where  beds  or  veins  encounter  faults  and  opera- 


18 


KEMPS   ORE  DEPOSITS. 


tions  are  brought  to  a  standstill,  the  continuation  is  usually  found 
as  follows,  according  to  Schmidt's  law.  If  the  fault  dips  or  hades- 
away  from  the  workings,  the  continuation  is  down  the  hade  ;  if  it 
dips  toward  the  workings,  it  should  be  followed  upward.  Such  a 
fault  is  called  a  normal  fault,  and  is  illustrated  in  the  figure 
on  p.  IV,  after  A.  A.  Blow.  This  is  a  natural  result  of  the  draw- 
ing apart  of  the  two  sides.  The  least  supported  mass  would  slip 
down  on  the  one  which  has  the  larger  base.  Less  commonly  the 
opposite  movement  results.  Thus  when  the  fault  is  due  to  com- 
pression, the  beds  pass  each  other  in  the  reverse  direction,  and 
what  is  called  a  reverse  fault  results.  The  accompanying  cut  il- 
lustrates a  very  extended  one  in  the  southern  Appalachians. 
While  we  would  naturally  think  of  a  reversed  fault  as  resulting 


StCT/ON  /. 


^^^^^^^V^-fr^^S-^^  Coiuiasauga  Shales 


*    Cohuttw  Conytomei-alfr 


Ocoee  State 
Knox  Dolomite 


FIG.  4. — Reversed  fault  at  Holly  Creek,  near  Dalton,  Ga.    After  C.  W* 
Hayes,  Bull.  G.  S.  A.,  Vol.  II.,  PL  3,  p.  152. 

from  a  compressive  strain,  in  that  in  this  case  the  lower  wedged- 
shaped  portion  would  be  forced  under  the  upper  one,  yet  normal 
faults  can  likewise,  in  instances,  be  explained  by  compression.  If 
we  consider  the  fault  to  be  caused  by  the  vertical  thrust  or  com- 
ponent, that  would  always  be  present  in  the  compression  of  a 
completely  supported  arch,  this  would  tend  to  heave  upward  the 
portion  next  the  fissure,  that  had  the  larger  base.  Along  an  in- 
clined fracture  such  portion  is  manifestly  the  under  one.  It  is  also 
important  to  note  whether  the  fault  plane,  both  in  normal  and  in 
reversed  faults,  cuts  inclined  beds  in  the  direction  of  the  dip  or 
across  it.  (See  Margerie  and  Heim,  Dislocation  der  Erdrinde^ 
Zurich,  1888.) 

1.02.09.     The  movement  of  the  walls  on  each  other  produces 
grooves  and  polished  surfaces  called  slickensides,  or  slips.     They 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  19 

are  usually  covered  with  a  layer  of  serpentine  or  talc  or  some 
such  secondary  product.  The  strain  caused  by  the  movement  may 
in  rare  instances  leave  the  slips  in  such  a  state  of  tension  that 
when,  from  any  cause  such  as  excavation,  the  pressure  is  relieved, 
they  will  scale  off  with  a  small  explosion.  (See  A.  Strahan,  "  On 
Explosive  Slickensides,"  Geological  Magazine,  iv.  401,  522.)  Ob- 
servations on  the  directions  of  slips  may,  in  cases  of  doubt,  throw 
some  additional  light  on  the  direction  of  the  movement  which 
caused  the  fault.  But  the  best  guide  in  stratified  rocks  is  a  knowl- 
edge of  the  succession  of  the  beds  as  revealed  by  drill  cores  or  ex- 
cavations. Attempts  have  been  made  to  deduce  mathematical 
formulas  for  the  calculation  of  the  amount  of  downthrow  or  up- 
throw, and  when  sufficient  data  are  available,  as  is  often  the  case 
in  coal  seams,  this  may  be  done.  The  methods  depend  on  the 
projection  of  the  planes  in  a  drawing,  on  the  principles  of  analytical 
geometry,  and  on  the  calculation  of  the  displacements  by  means  of 
spherical  trigonometry.  (See  G.  Koehler,  Die  Storungen  der  Gdnge, 
Plotze  und  Lager,  Leipzig,  1886  ;  William  Engelmann.  A  transla- 
tion by  TV".  B.  Phillips,  entitled,  "Irregularities  of  Lodes,  Veins, 
and  Beds,"  appeared  in  the  Engineering  and  Mining  Journal,  June 
.25,  1887,  p.  454,  and  July  2,  1887,  p.  4.  A  very  excellent  paper, 
having  a  quite  complete  bibliography,  is  F.  T.  Freeland's  "  Fault 
Rules,"  M.  E.,  June,  1892.)  Prof.  Hans  Hoefer  has  called  attention 
to  the  fact  that  in  faulting  there  is  frequently  a  greater  displace- 
ment in  one  portion  of  the  fissure  than  in  a  neighboring  part,  and 
«ven  a  difference  of  hade.  This  causes  a  twisting  or  circular  move- 
ment of  one  wall  on  the  other,  and  needs  to  be  allowed  for  in  some 
-calculations.  (  Oestereich.  Zeitschrift  fur  Berg-  und  Huettenwesen, 
Vol.  XXIX.  An  abstract  in  English  is  given  by  R.  TV.  Raymond, 
M.  E.,  February,  1882.)  In  the  Engineering  and  Mining  Journal 
for  April  and  May,  1892,  a  quite  extended  discussion  of  faults  by 
several  prominent  American  mining  engineers  and  geologists  is 
given,  apropos  of  the  question  raised  by  Mr.  J.  A.  Church  as  to 
whether  fissure  veins  are  more  regular  on  the  dip  or  on  the  strike. 
In  a  relatively  uniform  massive  rock  the  regularity  should  be 
greater  on  the  dip,  but  in  inclined  and  diversified  stratified  rocks 
too  many  variables  enter  to  warrant  any  sweeping  assertions.  In 
soft  rocks  like  shales  the  fissure  may  become  so  split  into  small 
stringers  as  to  be  valueless.  Again,  in  very  firm  rock,  where  there 
is  little  drawing  apart,  the  fissure  may  be  very  tight.  In  the  veins 
of  Newman  Hill,  near  Rico,  Colo,  (see  2.09.10),  the  fissure  is  so 

/^fc- 

f(  UNIT*'  H 


20  KEMPS   ORE  DEPOSITS. 

narrow  above  a  certain  stratum  as  practically  to  fail.  Quartzite 
is  a  favorable  rock  for  such  effect.  Despite  all  rules,  faults  are 
often  causes  of  great  uncertainty,  annoyance,  and  expensive  ex- 
ploration. 

1.02.10.  If  a  number  of  faults  succeed  one  another  in  a  short 
distance  they  are  called  "  step  faults."     An  older  and  completed 
vein  may  also  be  faulted  by  one  formed  and  filled  later.     In  such 
a   case  the  continuous  one  is  the   younger.     The    figure   below 
will  illustrate  each  case.     At  the  intersection  of  the  two,  the  later 
vein  is  often  richer  than  in  other  parts. 

1.02.11.  If  a  faulted  series  of  rocks  is  afterward  tilted  and 
eroded,  so  as  to  expose  a  horizontal  section  across  the  strike  of  the 
faulting  plane,  an  apparent  horizontal  fault  may  result  ;  or  if  the 
erosion  succeeds  normal  faulting  and  lays  bare  two  unconformable 
beds  each  side  of  the  fissure,  a  lack  of  correspondence  in  plan  as, 


Cross          V^fe=— *^  VeTn  C 


FIG.  5. — Illustration  of  one  vein  faulting  another  at  Newman  Hill,  near 
Rico,  Colo.     After  J.  B.  Parish,  Proc.  Colo.  Sci.  Soc.,  April  4,  1892. 

well  as  in  section  may  be  seen.  Faulting  fractures  are  seldom 
straight  ;  on  the  contrary,  they  bend  and  corrugate.  When  the 
walls  slip  past  each  other,  they  often  stop  with  projection  opposite 
projection,  and  depression  opposite  depression.  These  irregularities 
cause  pinches  and  swells  in  the  resulting  cavity,  and  constitute  one 
of  the  commonest  phenomena  of  veins.  Fissures  also  gradually 
pinch  out  at  their  extremities,  or  break  up  into  various  ramifica- 
tions that  finally  entirely  cease.  They  also  pass  into  folds,  as 
stated  above. 

1.02.12.  /Secondary  Modifications  of  Cavities. — Fractures  and 
cavities  of  all  sorts  speedily  become  lines  of  subterranean  drainage. 
The  dissolving  power  of  water,  and  to  a  much  smaller  degree  its 
eroding  power,  serve  to  modify  the  walls  very  greatly.  An  en- 
largement may  result,  and  what  was  perhaps  a  small  joint  or  fis- 
sure may  become  a  waterway  of  considerable  size.  This  is 
especially  true  in  limestones,  in  which  great  caverns  (like  the 


ON  THE  FORMATION  OF  CAVITIES  IN  ROCKS.  21 

Mammoth  Cave  and  Luray's  Cave)  are  excavated.  Caves  are, 
however,  almost  always  due  to  surface  waters,  and  do  not  extend 
below  the  permanent  water  level  unless  they  have  been  depressed 
after  their  formation.  (See  J.  S.  Curtis,  Monograph  VII.,  U.  S. 
Geol.  Survey,  Chap.  VIII.) 

The  solvent  action  of  water  is  vastly  augmented  by  the  car- 
bonic acid  which  it  gathers  from  the  atmosphere,  and  this  is  the 
chief  cause  of  the  excavations  wrought  by  it  in  limestones.  Pure 
cold  water  has  comparatively  small  dissolving  and  almost  no  ero- 
sive power.  It  has  also  been  advocated  that  various  acids  which 
result  from  the  decay  of  vegetable  matter  aid  in  such  results.  (A. 
A.  Julien,  Amer.  Asso.  Adv.  Sci.,  1879,  p.  311.)  This  may  be  true, 
but  in  general  carbonic  acid  is  the  chief  agent.  Iron  in  minerals 
falls  an  easy  prey,  as  well  as  calcium,  and  is  dissolved  out  in  large 
amount.  (See  Example  1.)  When  charged  with  alkaline  carbon- 
ates, water  has  the  power  to  attack  other  less  soluble  minerals,  such 
as  quartz  and  the  silicates,  and  by  such  action  the  walls  of  a 
cavity  in  the  crystalline  rocks  may  be  much  affected. 

1.02.13.  Waters  percolating  to  great  depths  in  the  earth,  or 
circulating  in  regions  of  igneous  disturbances,  become  highly 
heated,  and  this  too  at  great  pressure.  Under  such  circumstances 
the  solvent  action  is  very  strongly  increased,  and  all  the  elements 
present  in  the  rock-making  minerals  are  taken  into  solution. 
Alkaline  carbonates  are  formed  in  quantity  ;  silica  is  easily  dis- 
solved ;  alkaline  sulphides  result  in  less  amount ;  and  even  the 
heaviest  and  least  tractable  metals  enter  into  solution,  either  in  the 
heated  waters  themselves,  or  in  the  alkaline  liquors  formed  by  them. 
The  action  on  the  walls  of  cavities  and  courses  of  drainage  is  thus 
profound,  and  accounts  for  the  frequent  decomposed  character  of 
the  walls  and  the  general  lack  of  sharpness  in  their  definition. 
The  vast  amount  of  siliceous  material,  etc.,  deposited  by  hot  springs 
and  geysers  is  additional  evidence  of  its  importance. 

Magnesia  is  one  of  the  alkaline  earths  readily  taken  into  solu- 
tion by  carbonated  waters,  and  when  such  waters  again  meet  lime- 
stone the  effect  is  often  very  great,  and  constitutes  one  of  the 
most  important  methods  of  the  formation  of  cavities.  Solutions  of 
magnesium  carbonate,  on  meeting  calcium  carbonate,  effect  a  par- 
tial exchange  of  the  former  for  the  latter.  This  leaves  the  rock  a 
double  carbonate  of  calcium  and  magnesium,  which  is  the  composi- 
tion of  the  mineral  and  rock  dolomite.  The  process  is  therefore 
called  dolomitization.  (See  Example  25.)  It  may  bring  about  a 


22  KEMP'S   ORE  DEPOSITS. 

general  shrinkage  of  eleven  or  twelve  per  cent.  In  any  extended 
thickness  of  strata  this  would  cause  vast  shattering  and  porosity. 
As  an  illustration  of  its  results,  the  following  analyses  of  normal, 
unchanged  Trenton  limestone  of  Ohio,  and  of  well  drillings  from 
the  porous,  gas-bearing,  dolomitized  portions  of  the  same,  are 
given.  They  are  taken  from  a  paper  by  Edward  Orton.  (Amer. 
Manuf.  and  Iron  World,  Pittsburg,  Dec.  2,  1887.) 

CaC03.  MgC08.  Fe203.Al203.  SiO2. 

Unchanged  Trenton  limestone... 79. 30  0.92  7.00  12.00 

...82.36  1.67  0.58  12.34 

Dolomitized  "  "  ...53.50  43.50  1.25  1.70 

...51.78  36.80 

1.02.14.  Late  studies  in  ore  deposits  by  Posepny,  Curtis,  and 
Emmons  indicate  also  that  solutions  of  metallic  ores  may  effect  an 
interchange  of  their  contents  with  the  carbonate  of  calcium  or 
magnesium,  in  limestones  and  dolomites,  leaving  an  ore  body  in 
place  of  the  rocks.  This  change  is  effected  molecule  by  molecule, 
and  is  spoken  of  as  a  metasomatic  interchange  or  replacement. 
(See  Example  30.)  By  "metasomatic"  is  meant  an  interchange 
of  substance  without,  as  in  pseudomorphs,  an  imitation  of  form. 
Alteration  of  the  metallic  ores  may  follow  and  occasion  cavities 
from  shrinkage.  (See  Example  36,  and  Curtis,  on  Eureka,  Nev., 
Monograph  VIII.,  IT.  S.  Geol  Survey,  Chap.  VIII.) 


tJS  ' 


CHAPTER    III. 

THE  MINERALS  IMPORTANT  AS  ORES  ;  THE  GANGUE  MINERALS, 
AND  THE  SOURCES  WHENCE  BOTH  ARE  DERIVED. 

1.03.01.  The  minerals  which  form  the  sources  of  the  metals 
are  almost  without  exception  included  in  the  following  compounds  : 
the  sulphides,  the  related  compounds  of  arsenic  and  antimony,  ox- 
ides and  oxidized  compounds  such  as  hydrous  oxides,  carbonates, 
sulphates,  phosphates,  and  silicates,  and  one  or  two  compounds  of 
chlorine.     A  few  metals  occur  in  the  native  state.     All  the  other 
mineral  compounds  such  as  a  chromate  or  two,  a  bromide  or  iodide, 
etc.,  are  rarities.     It  may  be  said  that  nine  tenths  of  the  produc- 
tive ores  are  sulphides,  oxides,  hydroxides,  carbonates,   and  na- 
tive metals.     The  ores  of  each  metal  are  subsequently  outlined 
before  its  particular  deposits  are  described. 

1.03.02.  The  most  common  gangue  mineral  is  quartz,  while  in 
less    amount   are    found    calcite,  siderite,  barite,    fluorite,  and  in 
places  feldspar,  pyroxene,  hornblende,  rhodonite,  etc.     The  silicates 
are  chiefly  present  where  the  gangue  is  a  rock  and  the  ore  is  dis- 
seminated through  it.     All  the  common  rocks  serve  in  this  capaci- 
ty in  one  place  or  another. 

1.03.03.  Source  of  the  Metals. — The  metallic  contents  of  the 
minerals    which    constitute  ores  must  logically  be  referred  to   a 
source,  either  in  the  igneous  rocks  or  in  the  ocean.     If  the  nebular 
hypothesis  expresses  the  truth, — and  it  is  the  best  formulation  that 
we  have, — all  rocks,  igneous,  sedimentary,  and  metamorphic,  must 
be  traced  back  to  the  original  nebula.     This,  in  cooling,  afforded  a 
fused  magma,  which  chilled  and  assumed  a  structure  analogous  to 
the  igneous  rocks  with  which  we  are  familiar.    Igneous  rocks  must 
thus  necessarily  be  considered  to  have  furnished  by  their  erosion 
and  degradation  the  materials  of  the  sedimentary  rocks  ;  while 
igneous  and  sedimentary  have  alike  afforded  the  substances  whose 
alterations  have  produced  the  metamorphic  rocks.     It  may  also 
be   true  that  eruptive  rocks,   especially  when   basic,   have   been 


24  KEMP'S   ORE  DEPOSITS. 

formed,  by  the  oxidation  and  combination  with  silica,  of  inner 
metallic  portions  of  the  earth,  for  such  is  one  of  our  most  reason- 
able explanations  of  volcanic  phenomena,  suggested  alike  by  the 
composition  of  basalts,  by  the  high  average  specific  gravity  of  the 
globe,  and  by  analogy  with  meteorites. 

1.03.04.  As  opposed  to  this  conception,  there  are  those  who 
would    derive  the  metallic  elements  of  ores  from  the  ocean,  in 
which  they  have  been   dissolved  from  its  earliest    condensation. 
Thus  it  is  said  that  substantially  all  the  metals  are  in  solution  in 
sea  water.     From  the  sea  they  are  separated  by  organic  creatures, 
it  may  be,  through  sulphurous  precipitation,  attendant  on  the  de- 
cay   of   their   dead   bodies.     The   accumulations  of   the  remains 
of  organisms  bring  the  metals  into  the  sedimentary  strata.     Once 
thus    entombed,    circulation    may  concentrate    them    in    cavities. 
When  present  in  igneous  rocks,  the  latter  are  regarded  as  derived 
from  fused  sediments.     If  the  metallic  contents  of  sedimentary 
rocks  do  not  come  from  the  ocean  in  this  way,  the  igneous  rocks 
as  outlined  above  are  the  only  possible  source.     No  special  men- 
tion is  here  made  of  the  metamorphic  rocks,  because  in  their  origi- 
nal state  they  are  referable  to  one  or  the  other  of  the  two  remain- 
ing classes.     But  it  is  not  justifiable,  in  the  absence   of   special 
proof,  to  consider  them  altered  sediments,  any  more  than   altered 
igneous  rocks,  and  it  is  doubtless  true  that  the  too  generally  and 
easily  admitted  sedimentary  origin  for  our  gneisses  and  schists  has 
materially  hindered  the  advance  of  our  knowledge  of  them  in  the 
last  forty  years. 

1.03.05.  Microscopic  study  of  the  igneous  rocks    has   shown 
that,  with  few  exceptions,  the  rock-making  minerals  separate  from 
a  fused  magma   on   cooling  and  crystallizing,  in  a  quite    definite 
order.1     Thus  the  first  to  form  are  certain  oxides,  magnetite,  spec- 
ular hematite,  ilmenite,  rarely  chromite  and  picotite,  a   few   sili- 
cates, unimportant   in    this  connection  (zircon,  titanite),   and   the 
sulphides  pyrite  and  pyrrhotite.     Next  after  these  metallic  oxides, 
etc.,  the  heavy,  dark-colored,  basic  silicates,  olivine,  biotite,  au- 
gite,  and  hornblende,  are  formed.    All  these  minerals  are  character- 
ized by  high  percentages  of  iron,  magnesium,  calcium,  and  alumi- 
num.    They  are   very  generally   provided  with  inclusions  of  the 
first  set.     Following  the  bisilicates  in  the  order  of  crystallization, 

1  H.  Rosenbusch,  "Ueber  das  Wesen  der  Kornigen  und  Porphyrischen 
Structur  bei  Massengesteine,"  Neues  Jahrbuch,  1882,  ii.,  I. 


THE  MINERALS  IMPORTANT  AS  ORES,  ETC.  25 

come  the  feldspars,  and  after  these,  when  some  residual  silica  re- 
mains uncombined,  it  separates  as  quartz.  * 

1.03.06.  If  we  regard  the  igneous  rocks  as  the  source,  the 
metallic  elements  are  thus  to  be  ascribed  to  the  first  and  second 
series  of  crystallizations,  while  the  elements  of  the  gangue  minerals 
are  derived  from  the  last  three.  It  is  a  doubtful  point  whether 
the  less  common  metals,  such  as  copper,  silver,  and  nickel,  enter 
into  the  composition  of  the  dark  silicates  as  bases,**replacing  the  iron, 
alumina,  lime,  etc.,  or  whether  they  are  present  in  them  purely 
as  inclusions  of  the  first  series.  F.  Sandberger 1  argues  in 
support  of  the  first  view,  but  his  critics,  notably  A.  W.  Stelzner, 
cast  doubt  upon  his  conclusions  on  the  ground  that  his  chemical 
methods  were  indecisive.  The  case  is  briefly  this  :  Sandberger,  as 
an  advocate  of  views  which  will  be  subsequently  outlined,  sep- 
arated the  dark  silicates  of  a  great  many  rocks.  By  operating  on 
quantities  of  thirty  grams  he  proved  the  presence  in  them  of  lead, 
copper,  tin,  antimony,  arsenic,  nickel,  cobalt,  bismuth,  and  silver, 
and  considered  these  metals  to  act  as  bases.  The  weak  point  of  the 
demonstration  consists  in  dissolving  out  from  the  powdered  silicate 
any  possible  inclusions.  There  seems  to  be  no  available  solvent 
which  will  take  the  inclusions  and  be  without  effect  on  the  silicates. 
This  is  the  point  attacked  by  the  critics,  and  apparently  with 
reason.  It  is,  however,  important  to  have  shown  the  presence  .of 
these  metals,  even  though  their  exact  relations  be  thus  doubtful. 
Quite  recently  in  a  series  of  "  Notes  on  Chilean  Ore  Deposits " 
(Tschermaks  Min.  und  Petrog.,  Mitth.  XIL,  p.  195)  Dr.  Mori  eke 
mentions  native  gold  in  pearlstone  (obsidian)  from  Guanaco,  in 
skeleton  crystals  in  the  glass,  as  inclusions  in  perfectly  fresh 
plagioclase  and  sanidine  crystals,  and  in  spherulites.  The  existence 
of  silver  in  quartz-porphyry  has  been  demonstrated  in  this  country 
by  J.  S.  Curtis,  at  Eureka,  Nev.;2  both  the  precious  metals  have 
been  shown  by  G.  F.  Becker  to  be  in  the  diabase  near  the  Com- 


1  The  principal  paper  of  Professor  Sandberger  is  his  "  Untersuchungen 
iiber  Erzgange,"  1882,  abstracted  in  the  Engineering  and  Mining  Journal, 
March  15,  22,  and  29,  1884;  but  a  long  series  of  others  might  be  cited  in 
which  the  investigations,  notably  at  Pribram,  Bohemia,  are  interpreted 
as  indicated  above    A.  W.  Stelzner,  B.  and  H.  Zeit. ,  xxxix. ,  No.  3.  Zeitsch. 
d.d.g.  GeselL,  xxxi.  644.     "  Die  Lateral-secrrtions-Theorie,  etc."  Reprint 
Freiberg,  1889. 

2  Monograph  VII.,  U.  S.  Geol.  Survey. 


26  KEMP'S  ORE  DEPOSITS. 

stock  Lode  ; l  and,  by  the  same  investigator,  antimony,  arsenic, 
lead,  copper,  gold,  and  silver  were  proved  to  be  contained  in  the 
granite  near  Steamboat  Springs,  Nev.2  S.  F.  Emmons  has  also 
shown  that  the  porphyries  at  Leadville  contain  appreciable,  though 
small,  amounts  of  silver.3  Of  forty-two  specimens  tested,  thirty- 
two  afforded  it ;  of  seventeen  tested  for  lead,  fourteen  yielded  re- 
sults. Undoubtedly  the  multiplication  of  tests  will  show  similar 
metallic  contents  in  other  regions.  Thus  the  augite  of  the  eastern 
Triassic  diabase  will  probably  yield  copper,  for  this  metal  is  abun- 
dant in  connection  with  the  outflows. 

1.03.07.  That  the  metals  are  so  generally  combined  with  sul- 
phur in  ore  deposits  seems  to  be  due  to  the  extended  distribution 
of  this  element,  and  to  its  being  a  vigorous  precipitating  agent  of 
nearly  all  the  metals  at  the  temperatures  and  pressures  near  the 
surface.     Sulphur  is  widespread  as  pyrite,  an  original  mineral  in 
many  igneous  rocks,  and  one  much  subject  to  alteration  ;  while 
sulphuretted  hydrogen   is   Qomnion   in  waters    from   sedimentary 
rocks,  and  is  a  very  general  result  of  organic  decomposition.     Xat- 
ural  gas  and  petroleum  from  limestone  receptacles  almost  always 
contain  it.     (See,  in  this  connection,  J.  F.  Kemp,  "  The  Precipita- 
tion of  Metallic  Sulphides   by  Natural  Gas,"    Engineering   and 
Mining  Journal,  Dec.  13,  1890.)     Many  sulphides,  too,  are  soluble 
under  the  pressures  and  temperatures  prevailing  at  great  depths, 
but  are  deposited  spontaneously  at  the  pressures  and  temperatures 
prevailing  at  or  near  the  surface. 

1.03.08.  Where   veins  occur  in   igneous  rocks  the  bases   for 
gangue  minerals  have  been  obtained  from  the  rock-making  silicates. 
Calcium  is  afforded  by  nearly  all  the  important  ones ;  silicon  is 
everywhere  present ;  barium  has  been  proved  in  many  feldspars, 
in  small  amount ;  and  magnesia  is  present  in  many  pyroxenes  and 
amphiboles.     Of  the  sedimentary  rocks,  limestone  of  course  affords 
unlimited  calcium,  and  recently  Sandberger  reports  that  he  has 
identified  microscopic  crystals  of  barite  in  the  insoluble  residues  of 
one.     (Sitzungsberichte  d.  Math.  phys.  Classe  d.  k.  bayer,  Akad.  d. 
Wiss.,  1891,  xxi.  291.)     This  is  of  interest,  as  barite  is  such  a  com- 
mon gangue  in  limestone. 

1.03.09.  It  may  be  remarked  that  the  natural  formation  of  both 

1  Monograph  III.,  U.  S.  Geol.  Survey. 
8  Monograph  XIII. ,  U.  S.  Geol.  Survey. 
8  Monograph  XII. ,  U.  S.  Geol.  Survey. 


THE  MINERALS  IMPORTANT  AS  ORES,  ETC.  27 

ore  and  gangue  minerals  has  doubtless  proceeded  in  nature  with 
great  slowness,  and  from  very  dilute  solutions.  Both  classes  ex- 
hibit a  tendency  to  concentrate  in  cavities,  even  from  a  widely 
dispersed  condition  through  great  masses  of  comparatively  barren 
rock.  The  formation  may  have  proceeded  when  the  walls  were 
far  below  their  present  position  with  regard  to  the  surface,  so  that 
to  those  inclined  a  wide  latitude  for  speculation  on  origin  is 
afforded.  It,  is  also  possible  that  in  the  earlier  history  of  the  globe 
circulations  were  more  active  than  they  are  now — a  line  of  argu- 
ment on  which  a  conservative  writer  would  hesitate  to  enlarge. 


CHAPTER   IV. 

ON  THE  FILLING  OF  MINERAL  VEINS. 

1.04.01.  Bearing  in  mind  what  precedes,  the  preliminaries  for 
the  discussion  of  mineral  veins  are  set  in  order.     We  have  traced 
the  formation  of  cavities  by  the  shrinkage  of  rock  masses  in  cool- 
ing or  drying,  by  the  movements  and  disturbances  of  the  earth's 
crust  (which  are  far  the  commonest  and  most  important  causes), 
and  by  dolomitization.     The  enlargement  of  such  cavities  by  sub- 
terranean circulations  followed,  and  the  general  effect  of  waters, 
cold  and  heated.     The  sources  of  the  elements  of  the  useful  min- 
erals were  pointed  out  so  far  as  known.     All  these  general  and  in- 
disputable truths  assist  in  the   drawing  of  right  conclusions.     It 
should  be  emphasized,  as  will  appear  later,  that   mineral  veins  or 
cavity  fillings  do  not   embrace  all  metalliferous  deposits.     On  the 
contrary,  the  deposits  which   either  form  beds  by  themselves,  or 
which  are  disseminated  through  beds  of  barren  rock  arid  are  of  the 
same  age  with  them,  do  not  enter  into  the  discussion.     They  are 
characterized  by  being  younger  than  their  foot  walls  and  older 
than  the  hanging.     Their  geological  structure  is  far  simpler,  and, 
as  will  appear  in  the  discussion  of  particular  examples,  the  work- 
ing out  of  their  origin  does  not  so  often  carry  the  investigator  into 
the  realms  of  speculation  and  hypothesis.     And  yet  it  is  not  to  be 
inferred  from  the  prominence  here  given  to  the  discussion  of  veins 
that  bedded  deposits  yield  to  them,  in  any  degree,  in  importance. 
Iron  ores,  for  instance,  are  often  in  beds. 

1.04.02.  Methods  of  Filling. — Methods  of  filling  were  summed 
up  a  very  long  time  ago  by  Yon  Herder  and  Yon  Cotta,1  as  fol- 
lows :    1.  Contemporaneous   formation.     2.  Lateral  secretion.     3. 
Descension.     4.  Ascension  by  (a)  infiltration,  or   (b)  sublimation 
with  steam,  or  (c)  by  sublimation  as  gas,  or  (d)  by  igneous  injec- 
tion.    To  these  should  be  added  the  more  recent  theory  of  (5)  re- 

1  Erzlagerstatten,  2d  ed.,  1859,  Vol.  I.,  p.  172. 


ON  THE  FILLING  OF  MINERAL  VEINS.  29 

placement,  which,  however,  is  rather  a  method  of  precipitation 
than  of  derivation.  No  one  longer  believes  in  contemporaneous  for- 
mation, and  descension  has  an  extremely  limited,  if,  indeed,  any 
application.  Ascension  by  sublimation  as  gas  or  with  steam,  or  by 
igneous  injection,  has  few,  if  any,  supporters.  The  discussion  is 
practically  reduced  to  lateral  secretion  and  to  ascension  by  infiltra- 
tion. 

1.04.03.  By  lateral  secretion  is  understood  the  derivation  of 
the  contents  of  a  vein  from  the  wall  rock.     The  wall  rock  may 
vary^  in  character  along  the  strike  and  in  depth.     Three  interpreta- 
tions may  be  made,  two  of  which  approach  a  common  middle  ground 
with  ascension  by  infiltration.     It  may  first  be  supposed  that  the 
vein  has  been  filled  by  the  waters  near  the  surface  which  are  known 
to  be  soaking  through  all  bodies  of  rock,  even  where  no  marked 
waterway  exists,  and  which  seep  from  the  walls  of  any  opening 
that  may  be  afforded.     Being  at  or  within  comparatively  short 
distances   of   the  surface,  the  waters  are  not  especially  heated. 
As  they  emerge  to  the  oxidizing  and  evaporating  influence  of  the 
air  in  the  cavity,  their  burden  of  minerals  is  deposited  as  layers  on 
the  walls.     The  second  interpretation   supposes  the  walls  to  be 
placed  during  the  time  of  the  filling  at  considerable  depth  below 
the  surface,  so  that  the  percolating  waters  are  brought  within  the 
regions  of    elevated  temperature  and    pressure.      Essentially    the 
same  action  takes  place  as  in  the  first  case.     The  third  interpreta- 
tion increases  the  extent  of  the  rock  leached.     Thus  if  a  mass  of 
granite  incloses  a  vein  and  extends  to  vast  depths,  we  may  suppose 
the  waters  to  come  from  considerable  distances,  and  to  derive  their 
dissolved  minerals  from  a  great  amount  of  rock  of  the  same  kind 
as  the  walls.     Portions  of  this  may  even  be  in  the  regions  of  high 
temperature,  while  the  place  of  precipitation  is  nearer  the  surface. 
These  last  two  interpretations  have  much  in  common  with    the 
theory  of  ascension   by  infiltration,  and  on  this  common  middle 
ground  lateral-secretionists  and  infiltration-ascensionists  may  be  in 
harmony. 

1.04.04.  Ascension  by  Infiltration. — The  theory  of  infiltration 
by  ascension  in    solution  from  below  considers  that   ore-bearing 
solutions  have  come  from  the-  heated  zones  of  the  earth,  and  that 
they   rise   through  cavities,  and  at  diminished  temperatures  and 
pressures  deposit  their  burdens.     No  restriction  is  placed  on  the 
source  from  which  the  mineral  matter  has  been  derived.     Indeed, 
beyond  that  it  is  "  below,"  and  yet  within  the  limits,  reached  by 


30  KEMPS   ORE  DEPOSITS. 

waters,  all  of  which  have  descended  from  the  surface,  and  that  the 
metals  have  been  gathered  up  from  a  disseminated  condition  in  rocks, 
— igneous,  sedimentary,  and  metamorphic, — no  more  definite  state- 
ment is  possible.  This  theory  is  of  necessity  largely  speculative, 
because  the  materials  for  its  verification  are  beyond  actual  inves- 
tigation. 

1.04.05.  In  favor  of  lateral  secretion  the  following  arguments 
may  be  advanced.     I.  According  to  Sandberger,  actual  experience 
with  the  conduits,  either  natural  or  artificial,  of  mineral  springs, 
shows  that  a  deposit  seldom,  if  ever,  gathers  in  a  moving  current. 
It   is  only  when  solutions   come  to  rest   on  the  surface  and  are 
exposed  to  oxidation  and  evaporation  that  precipitation  ensues. 
Deposits  in  veins  have  therefore  formed  in  standing  waters,  whose 
slight  overflow  or  evaporation  would  be  best  compensated  by  the 
equally  slight  and  gradual  inflow  from  the  walls.    If  in  hot  springs 
there  were  a  strong  and  continuous  flow  from  below  and  discharge 
from  above,  the  mineral  matter  would  reach  the  surface.     (Sand- 
berger, Untersuchungen  uber  Erzgange,  Heft  I.)  Hence  the  deposit 
would  be  more  likely  to  gather  by  the  slow  infiltrations  from  the 
wall  rock,  which  would  stand  in  cavities  like  a  well.     We  have, 
however,    some  striking   instances   of   deposits   in    artificial   con- 
duits. 

Prof.  H.  S.  Munroe  has  called  the  writer's  attention  to  a  case 
recently  met  by  him.  The  fourteen-inch  column  pipe  of  a  pump 
at  the  Indian  Ridge  Colliery,  Shenandoah,  Penn.,  which  was  rais- 
ing ferruginous  waters,  became  reduced  in  diameter  to  five  inches 
within  two  years  by  the  deposit  of  limonite.  The  same  amount 
of  water  was  forced  through  the  five-inch  as  through  the  fourteen- 
inch.  By  figuring  out  the  stroke  and  cylinder  contents,  it  was 
found  that  in  the  clear  pipe  the  water  moved  162  feet  per  minute, 
and  in  the  contracted  pipe  1268  feet.  And  yet  the  deposit  gath- 
ered. The  conditions  necessitated  the  continuous  action  of  the 
pump,  and  it  was  not  idle  over  two  hours  in  each  two  months 
of  that  period.  The  boiler  feed-pipes  of  steamers  plying  on  the 
Great  Lakes  also  become  coated  with  salts  of  lime.  Years  ago  a 
disastrous  boiler  explosion  occurred  from  the  virtual  stoppage  of 
the  feed  by  this  precipitation. 

1.04.06.  II.     If  a  vein  were  opened  up,  in   mining,  which  ran 
through  two  different  kinds  of  rock,  and  if  in  the  one  rock  one 
kind  of  ore  and  gangue  minerals  were  found,  and  in  the  other  a 
different  set,  the  wall   rock  would  clearly  have  some  influence. 


ON  THE  FILLING  OF  MINERAL  VEINS.  31 

Thus  in  a  mine  at  Schapbach,  in  the  Black  Forest,  investigated  by 
Sandberger,  a  vein  ran  through  granite  and  gneiss.  The  mica  of 
the  granite  contained  arsenic,  copper,  cobalt,  bismuth,  and  silver, 
but  no  lead.  The  principal  ore  in  this  portion  was  gray  copper. 
The  mica  of  the  gneiss  contained  lead,  copper,  cobalt,  and  bismuth, 
and  the  vein  held  galena,  chalcopyrite,  and  a  rare  mineral,  schap- 
bachite,  containing  bismuth  and  silver,  but  probably  a  mixture  of 
several  sulphides.  No  two  ores  were  common  to  both  parts  of  the 
vein.  Another  well-established  foreign  illustration  is  at  Klausen, 
in  the  Austrian  Tyrol.  Lead,  silver,  and  zinc  occurred  in  the 
veins  where  they  cut  diorite  and  slates,  but  copper  where  mica, 
schist  and  felsite  formed  the  walls.  In  America  there  are  a  num- 
ber of  similar  cases.  At  the  famous  Silver  Islet  Mine1  on  Lake 
Superior  the  vein  runs  through  unaltered  flags  and  shales,  and 
then  crosses  and  faults  a  large  diorite  dike.  When  the  diorite 
forms  the  walls,  the  vein  carries  native  silver  and  sulphides  of 
lead,  nickel,  zinc,  etc.,  but  where  the  flags  form  the  walls,  the 
vein  carries  only  barren  calcite.  Along  the  edges  of  the  estuary 
Triassic  sandstones  of  the  Atlantic  border,  where  they  adjoin 
Archaean  gneiss,  a  number  of  veins  are  found  carrying  lead  min- 
erals, while  in  the  sandstones  near  the  well-known  diabase  sheets 
and  dikes  are  others  carrying  copper  ores.  It  was  early  remarked 
by  J.  D.  Whitney  that  the  lead  was  usually  associated  with  the 
gneiss,  the  copper  with  the  diabase. 

1.04.07.  From  instances  like  these  it  is  inferred  that  the  ores 
were  derived  each  from  its  own  walls,  and  by  just  such  a  leaching 
action  by  cold  surface  waters  as  is  outlined  above.  As  opposed 
to  this,  it  has  usually  been  claimed  that  each  particular  wall  ex- 
erted a  peculiar  selective  and  precipitating  action  on  the  metals 
found  adjacent  to  it  and  none  on  the  others  ;  so  that  if  a  solution 
arose  carrying  both  sets,  each  came  down  in  its  particular  surr 
roundings,  while  the  others  escaped.  Dr.  W.  P.  Jenney  has  called 
the  writer's  attention  to  such  a  case.  The  Head  Centre  mine,  in 

1  W.  M.  Courtis,  "  On  Silver  Islet,"  Engineering  and  Mining  Journal, 
Dec.  21,  1878.     M.  E.,  V.  474. 

E.  D.  Ingall,  Geol  Survey  of  Canada,  1887-88,  p.  27,  H. 

F.  A.  Lowe,  "  The  Silver  Islet  Mine,"  etc.,   Engineering  and  Mining 
Journal,  Dec.  16,  1882,  p.  321. 

T.  MacFarlane,  "Silver  Islet,"  M.  E.,  VIII.  226.  Canadian  Naturalist* 
IV.  37. 

McDermott,  Engineering  and  Mining  Journal,  January,  1877. 


32  KEMP'S   ORE  DEPOSITS. 

the  Tombstone  district,  Arizona,  is  on  a  vein  which  pierces  slates, 
and  in  one  place  forty  feet  of  limestone.  In  the  slates  it  carried 
high-grade  silver  ores,  with  no  lead,  but  in  the  limestone,  lead-sil- 
ver ores.  A  rock  like  limestone  might  well  exercise  a  precipita- 
ting action,  which,  however,  we  cannot  attribute  to  rocks  composed 
of  the  more  inert  silicates.  Again,  it  has  been  said  that  the  solu- 
tions coming  from  below  have  varied  in  different  portions  of  the 
vein  or  at  different  periods.  An  earlier  opening  would  thus  be 
filled  with  one  ore,  a  later  opening  with  another.  This  is  hy- 
pothetical, but  has  been  advanced  for  Klausen  by  Posepny.  (Ar- 
chiv  f.  Praktisclie  Geologic,  p.  482.)  A  further  general  objection 
to  the  first  interpretation  of  lateral  secretion  is  the  weak  dissolv- 
ing power  of  cold  surface  waters,  and  this  is  a  very  serious  one. 

1.04.08.  As  opposed  to  the  second  interpretation,  it  may  be 
advanced  that  precipitation  in  a  cavity  at  a  great  depth  would  be 
retarded  by  the  heat  and  the  pressure,  to  just  that  extent  to  which 
solution  in  the  neighboring  walls  would  be  aided.     The  tempera- 
ture and  pressure  being  practically  the  same,  the  tendency  to  re- 
main in  solution  would  be  great  until  the  minerals  had  reached  the 
upper  regions  and  filled  the  cavity  by  ascension.     Under  such  cir- 
cumstances ores  would  only  be  deposited  below,  by  some  such  ac- 
tion as  replacement.     To  the  third  interpretation  no  theoretical  ob- 
jections can  be  made. 

1.04.09.  Infiltration  by  Ascension. — On  the  side  of  infiltration 
by  ascension,  if  two  veins  or  sets  of  veins  were  found  in  the  same 
wall  rock,  but  with  different  kinds  of  ores  and  minerals,   the  con- 
clusion would  be  irrefutable  that  the  respective  solutions   which 
formed  them  had  come  from  two  different  sources  below.     Thus  at 
Butte,  Mont.,  there  is  a  great  development  of  a  dark,  basic  granite. 
It  contains  two  series  of  veins,  of  which  the  southern  produces  copper 
sulphides  in  a  siliceous  gangue,  the  northern  sulphides  of  silver, 
lead,  zinc,  and  iron,  also  in  a  siliceous  gangue,  but  abundantly  associ- 
ated with  manganese  minerals,  especially  rhodonite.    No  manganese 
occurs  in  the  copper  belt,  nor  is  any  copper  found  in  the  silver  belt. 
Such  results  could  originate  only  in  different,  deep-seated  sources. 
Again,  at  Steamboat  Springs,  Nev.,  and  Sulphur  Bank,  Cal.,  the  hot 
springs  are  still  in  action  and  are  bringing  their  burdens  of  gangue 
and  ore  to  the  surface.     The  former  has  afforded  a  long  series  of 
metals,  the  latter  chiefly  cinnabar.    G.  F.  Becker1  has  shown  that 
the  cinnabar  probably  comes  up  in  solution  with  alkaline  sulphides. 

1  G.  F.  Becker,  "  Natural  Solutions  of  Cinnabar,  Gold,  and  Associated 


ON  THE  FILLING  OF  MINERAL  VEINS.  33 

1.04.10.  Replacement. — The  conception  of  replacement  is  one 
that  has  been  applied  of  late  years  by  some  of  the  most  reliable 
observers.     About  1873  it  appears  to  have  been  first  extensively 
developed  by  Franz  Posepny,  an  Austrian  geologist,  in  relation  to 
certain  lead-silver  deposits  at  Raibl,  in  the  Province  of  Kaernthen. 
About  the  same  time  it  was  suggested  by  Pumpelly,   then  State 
Geologist   of  Missouri,    to  Adolf  Schmidt,  who  was  engaged  in 
studying  the  iron  deposits  of  Pilot  Knob  and  Iron  Mountain   (see 
Examples  11  and  lla),  and  by  Schmidt  it  was  considered  applicable 
to  them.     ("Iron  Ores  and  Coal  Fields,"  Missouri  Geol.  Survey, 
1873.)     Some  ten  years  later  J.  S.  Curtis  based  his  explanation  of 
the   formation  of  the  Eureka  (Nev.)  lead-silver  deposits  on  the 
same  idea,  and  according  to  Emmons  (1886)  it  holds  good  for  Lead- 
ville.     R.  D.  Irving,  who  credited  Pumpelly  with  bringing  it  to  his 
attention,  published  in  1886  an  explanation  of  the  hematite  beds  of 
the  Penokee-Gogebic  range  (Example  9c'),  in  which  the  idea  is  ap- 
plied, and  Van  Hise  has  since  elaborated  it.     In  the  process  of  re- 
placement no  great  cavity  is  supposed  to  exist  previously.     There 
is  little,  in  fact,  but  a  circulation  or  percolation  of  ore-bearing  solu- 
tions which  exchange  their  metallic  contents,  molecule  by  molecule, 
for  the  substance  of  the  rock  mass.     We  would  not  expect  the  ore 
body  to  be  as  sharply  defined  against  the  walls  as  when  it  filled  a 
fissure,  but  rather  to   fade  into  barren  material.     Thus   rock  may 
be  impregnated   but  not  entirely  replaced,  and,  while  apparently 
unchanged,  yet  carry  valuable  amounts  of  ore.     Some  of  the  ores 
of  Aspen,  Colo.  (Example  30c?),  are  at  times  only  to  be  distinguished 
by  assay  from  the  barren  limestones.     Yet    decomposition   may 
bring  out  the  limits  of  each. 

1.04.11.  The   chemistry  of  the  replacement  process  is  none  too 
well  understood,  but  it  presents  fewer  difficulties  when  applied  to  a 
soluble  rock,  like  limestone  or  dolomite,  than  when  rocks  composed 
of  silicates  and  quartz   have  given  away  to  ores.     Acid  solutions 
would  readily  yield  to  calcium  carbonate;  but  if  the  metals  are  pres- 
ent as  sulphates,  some  reducing  agent,  such  as  organic  matter,  is 
necessary    in  order  to  change  the  metallic  sulphate  to  sulphide.1 
Or  else,  if  the  metallic  sulphides  come  up  in  solution  with  alkaline 
sulphides,  some  third  agent  is  needed  to  remove  the  calcium  car- 
Sulphides,''  Amer.  Jour.  Sci.,  III.,  xxxiii.  199;    Eighth  Ann.  Rep.  Direc- 
tor U.  S.  Geol.  Survey;  Monograph  XIII. ,  U.  S.  Geol.  Survey,  p.  965. 

1  Compare  S.  F.  Emmons,  "  On  the  Replacement  of  Leadville  Limestones 
and  Dolomites  by  Sulphides,"  Monograph  XII.,  U.  S.  Geol.  Survey,  p.  563. 


34  KEMP'S  ORE  DEPOSITS. 

bonate,  pari  passu,  just  before  the  metallic  sulphide  is  precipitated. 
It  must  be  confessed  that  for  enormous  bodies  of  ore,  like  those  of 
Leadville,  the  small  amount  of  organic  matter  present  seems  hard- 
ly equal  to  the  task  assigned  it,  and  the  delicate  balance  of  the  lat- 
ter case — causing  deposition  to  tread  so  closely  on  the  heels  of  rock 
removal,  in  order  to  avoid  assuming  an  extended  cavity — makes  it 
appear  that  the  entire  chemistry  of  the  process  is  perhaps  hardly 
understood. 

1.04.12.  When  silicate  rocks  are  replaced,  leaving  a  siliceous 
gangue,  the  process  may  have  been  somewhat  as  suggested  by  R. 
C.  Hills  for  the  mines  of  the  Summit  district,  Rio  Grande  County, 
Colorado.  (See  Proc.  Colo.  Sci.  Soc.,  Vol.  I.,  p.  20.)  Alkaline  solu- 
tions remove  silica  and  have  slight  action  on  silicates,  but  solutions 
acid  with  sulphuric  acid  attack  silicates,  such  as  feldspar  and  bio- 
tite,  remove  the  alumina  or  change  it  to  kaolin,  and  cause  the  sep- 
aration of  free  silica.  In  the  alteration  products  abundant  opportu- 
nity would  be  afforded  for  the  precipitation  of  sulphides,  which 
would  in  part  at  least  replace  the  rock.  Along  a  crack  or  line  of 
drainage  definite  walls  would  thus  easily  fade  out.  Such  phenome- 
na are  afforded  by  innumerable  ore  deposits  (see  R.  W.  Raymond, 
discussion  of  S.  F.  Emmons'  "  Notes  on  the  Geology  of  Butte, 
Mont.,"  M.  J£,  July,  1877),  and  often  come  under  the  notice  of 
every  one  familiar  with  mining.  Yet  we  cannot  but  hope  that 
in  the  future  our  knowledge  of  the  chemical  reactions  involved 
will  be  increased. 

It  may  again  be  stated  that  the  formation  of  ore  deposits  has 
proceeded  with  great  slowness,  and  the  solutions  bringing  the  met- 
als have  been,  beyond  question,  very  dilute.  The  extremely  small 
amounts  of  the  metals  that  have  been  detected  in  relatively  large 
amounts  of  igneous  rocks,  even  by  the  most  refined  analytical  meth- 
ods, have  necessarily  made  the  progress  of  solution  a  protracted 
one.  Curtis  records  some  careful  observations  on  the  growth  of 
aragonite  at  Eureka,  Nev.,  where  he  found  that  in  three  weeks, 
so  long  as  wet  by  a  drop  of  water,  the  crystals  increased  in  one  case 
as  a  maximum,  five  eighths  of  an  inch,  and  in  another  three  eighths. 
But  this  was  where  the  whole  inclosing  mass  of  rock  consisted  of  the 
compound  deposited. 


CHAPTER  V. 

ON  CERTAIN  STRUCTURAL  FEATURES   OF  MINERAL  VEINS. 

1.05.01.  Banded  Structure. — Mineral  veins  sometimes  exhibit 
a  banded  structure,  by  which  is  understood  the  arrangement  of 
the  ore  and  gangue  in  parallel  layers  that  correspond  on  opposite 
walls.     They  are  most   conspicuous  where  the  walls  are  well  de- 
fined.    The  solutions  which  have  brought  the  minerals  have  varied 
from  time  to  time,  and  the  precipitated  coatings    correspond  to 
these  variations.     They  alternate  from  gangue  to  ore,  it  may  be, 
several  times  repeated.     The  ore  may  be  in  small  scattered  masses 
preserving  a  distinct  lineal  arrangement  in  the  midst  of  the  barren 
quartz,  calcite,  barite,  fluorite,  siderite,  etc.,  or  itself  be  so  abun- 
dant as  to  afford  a  continuous  parallel  streak.     The  commonest 
ores  so  observed  are  pyrite,  chalcopyrite,  galena,  blende,  and  the 
various  sulphides  of  silver.     The  veins  of  the  Reese  River  district, 
in  Nevada,  furnish  good  illustrations  of  alternating  ruby  silver 
ores  and  quartz.     Those    of  Gilpin  County,    Colorado   (Example 
1VO),  afford  alternations  of  pyrite,  chalcopyrite,  and  gangue.     (See 
figures  in  Endlich's  report,  Hayderfs  Survey,  1873,  p.  280.)     The 
Bassick  Mine,  in  Colorado,  has  pebbles  remarkably  coated.     The 
figure  on  p.  36  shows  a  vein  at  Newman  Hill,  near  Rico,  Colo. 

Banded  veins,  however,  except  of  a  rude  character,  are  not  com- 
mon in  this  country.  They  have  received  much  more  attention  in 
Germany,  where,  especially  near  Freiberg,  they  show  remarkable 
perfection.  The  famous  Drei  Prinzen  Spat  Vein,  figured  by  Yon 
Weissenbach  and  copied  in  many  books,  has  ten  corresponding  al- 
ternations of  six  different  minerals  on  each  wall. 

1.05.02.  A  line  of  cavities,  or  vuggs,  is  often  seen  at  the  cen- 
tral portion  of  a  vein,  into  which  crystals  of  the  last  formed  miner- 
als emerge,  forming  a  comb  (see  p.  36).     These  may  project  into 
each  other  and  interlock, — especially  if  quartz, — forming  a  comb 
in  comb.    The  same  may  occur  between  side  layers.     These  cavities 
are  a  most  prolific  source  of  finely  crystallized  minerals.    If,  after  the 


36 


KEMP'S   ORE  DEPOSITS. 


fissure — perhaps  at  the  time  small — has  become  once  filled,  subse- 
quent movements  take  place,  it  may  strip  the  vein  from  one  wall  and 
cause  a  new  series  of  minerals  to  be  deposited,  with  the  previously 
formed  vein  on  one  side  and  the  wall  rock  on  the  other.  This  oc- 
casions unsymmetrical  fillings.  But  it  may  also  happen  that,  with 
otherwise  symmetrical  fillings,  one  layer  may  be  lacking  on  one 
side  or  the  other.  Where  portions  of  the  wall  rock  have  been  torn 
off  by  the  vein  matter  in  these  secondary  movements,  they  may  be 
buried  in  the  later  deposited  vein  filling,  and  form  great  masses  of 
barren  rock  called  horses.  The  vein  then  forks  around  them.  If 
the  ore  and  the  gangue  have  partly  replaced  the  wall  in  deposition, 


East 


FIG.  6. — Banded  vein  at  Newman  Hill,  near  Rico,  Colo.    After  J.  B.  Far- 

ish,  Proc.  Colo.  Sci.  Soc.,  April  4,  1892;  Engineering  and  Mining 

Journal,  Aug.  20,  1892. 

unchanged  masses  of  wall  may  also  become  inclosed  and  afford 
horses  of  a  different  origin.  An  originally  forked  fissure  gives  an 
analogous  result. 

It  is  a  curious  fact  that  veins  are  often  most  productive  just  at 
the  split.  If  the  masses  are  small,  or  if  the  vein  fills  a  shattered 
strip  and  not  a  clean  fissure,  or  if  it  occupies  an  old  volcanic  con- 
duit, deposition  and  replacement  may  surround  unchanged  cores  of 
wall  rock  with  concentric  layers  of  ores  and  minerals.  Thus  the 
Bassick,  at  Rosita,  Colo.,  referred  to  above,  consists  of  rounded 
cores  of  andesite,  inclosed  in  five  concentric  layers  of  metallic  sul- 
phides. The  Bull  Domingo,  in  the  same  region,  exhibits  shells  of 
galena  and  quartz  mantling  nodules  of  gneiss.  Such  cores  strongly 


ON  STRUCTURAL  FEATURES   OF  MINERAL    VEINS.      37 

resemble  rounded,  water-worn   boulders,   a   similarity    which  has 
suggested  some  rather  improbable  hypotheses  of  deposition. 

1.05.03.  Clay  Selvage. — An  extremely  common  feature  is  a 
band  of  clay,  most  often  between  the  vein  matter  and  the  wall. 
This  is  called  a  selvage,  gouge,  flucan,  clay  seam,  or  parting.  It 
may  come  in  also  between  layers  of  different  minerals,  and  even 
rests  as  a  mantle  on  the  crystals  which  line  cavities.  It  is  at  times 
the  less  soluble  portion  left  by  the  decay  and  removal  in  solution 
of  wall  rock  (residual  clay),  at  times  the  comminuted  material  re- 
sulting from  the  friction  of  moving  walls  (attrition  clay),  and 
again  it  may  be  taken  up  by  currents  and  redeposited  from  bodies 
of  the  first  two  sorts.  Such  layers  of  clay,  being  wellnigh  imper- 
vious to  water,  may  have  exercised  an  important  influence  in  di- 
recting the  subterranean  circulations.  (See  Becker  on  the  Corn- 
stock  Lode,  2.11.19.) 

1.05.04.  Pinches,  Swells,  and  Lateral  Enrichments.  —  The 
swells  and  pinches  of  veins  have  been  referred  to  above  and  ex- 
plained. Aside  from  these  thicker  portions  of  the  ore,  it  is  often 
seen  that  the  richer  or  even  the  workable  bodies  follow  certain 
more  or  less  regular  directions,  forming  so-called  "  chutes."  They 
probably  correspond  to  the  courses  taken  and  followed  by  the 
richer  solutions.  J.  E.  Clayton  observed  that  they  follow  the  di- 
rections of  the  slips,  or  striae,  of  the  walls  rather  more  often  than 
not,  and  in  the  west  this  disposition  or  tendency  is  called  Clayton's 
law.  Chute  is  sometimes  spelled  "shoot  "  or  "shute."  Chimney 
and  ore-cource  are  synonyms  of  chute.  Bonanza  is  used,  especially 
on  the  Comstock  Lode,  to  indicate  a  localized,  rich  body  of  ore. 

Lateral  enrichments  are  caused  by  the  spreading  of  the  ore- 
bearing  currents  sidewise  from  the  vein,  and  often  along  particu- 
lar beds  of  rock,  which  they  may  replace  more  or  less  with  ore. 
Beds  of  limestone — it  may  be  quite  thin,  when  in  a  series  com- 
posed of  shales  or  sandstones — are  favorite  precipitants,  and  from 
such  lateral  enlargement  the  best  returns  may  be  obtained.  The 
valuable  ore  bodies  of  Newman  Hill,  near  Rico,  Colo.,  whose  inter- 
esting description  by  J.  B.  Parish  has  already  been  several  times 
cited,  are  found  as  lateral  enrichments  along  a  bed  of  limestone  less 
than  three  feet  thick  and  embedded  in  shales.  Above  the  lime- 
stone the  veins  practically  cease.  Lateral  enrichments  may  closely 
resemble  bedded  deposits  if  the  supply  fissures  are  relatively  small. 
This  interpretation  is  placed  by  W.  P.  Jenney  on  the  disseminated 
lead  ores  of  southeastern  Missouri  (2.15.09),  and  he  has  suggested 


38  KEMP'S   ORE  DEPOSITS. 

the  expressive  term   "  melon  vein,"  thus  comparing  them  with  a 
vine  and  its  melons. 

1.05.05.  Changes  in  Character  of  Vein  Filling. — In  discuss- 
ing the  influence  of  wall  rock  the    changes  that    occur   in  veins 
were  briefly  mentioned.    But  even  where  the  walls  remain  uniform 
there  is  always  variation  in  contents,  and  of  course  in  value,  from 
point  to  point.      Ore,  gangue,  horses,  and   walls   alternate   both 
longitudinally  and  in  depth,  and  such  changes  must  be  allowed  for 
and  averaged  by  keeping  exploration  well  in  advance  of  excava- 
tion.    Even   a  series  of  parallel  veins  may  all   prove  fickle.     In 
illustration  of  the  above  the  Marshall  tunnel  of  Georgetown,  Colo., 
may  be  cited.     It  cut  twelve  veins  below  their  actual  workings, 
and  every  one  was  barren  at  the  tunnel  though  productive  above. 
(J.  J.  Stevenson,  Wheeler's  Survey,  Geology,  Vol.  III.,  p.  351.) 

1.05.06.  Secondary  Alteration  of  the  Minerals  in  Veins. — It 
has  already  been  stated  that  the  chief  ore  minerals  in  vein  fill- 
ings are  sulphides.     Where  these  lie  above  the  line  of  permanent 
subterranean  water  they  are  exposed  to  the  oxidizing  and  hydrat- 
ing  action  of  atmospheric  waters,  which,  falling  on   the  surface, 
percolate  downward.     The  ores  are  thus  subjected  to  alternating 
soakings  and  dryings  which  encourage  alteration.     The  sulphides 
change  to  sulphates,  carbonates,  oxides,  or  hydrous  forms  of  the 
same,  and  the  metallic  contents  are  in  part  removed  in  the  acid 
waters  which  are  also  formed.     Pyrite,  which  is  the  most  wide- 
spread of  the  sulphides,  becomes  limonite,  staining  everything  with 
its   characteristic    color.      Galena   becomes  cerusite  or  anglesite. 
Blende  affords  calamine  and  smithsonite.     Copper  ores,  of  which 
the  usual"  one  is  chalcopyrite,  change  to  malachite,  azurite,  chryso- 
colla,  cuprite,  and  melaconite,  and  to  the  sulphide  chalcocite.     The 
silver  sulphides  afford  cerargerite.     The  rarer  metals  alter  to  cor- 
responding compounds  of  less  frequency.     These  upper  portions 
are  also  more  cellular  and  porous,  being  at  times  even  earthy.    The 
rusty  color  from  the  presence  of  limonite  often  marks  the  outcrop 
and  is  of  great  aid  to  the  prospector.     It  has  been  called  the  iron 
hat,  or  gossan.     This  feature  has  important  economic  bearings. 
The   character  of  ores  may  entirely  change  at  a  definite  point  in 
depth,  and  the  later  products,  if  not  lower  in  grade,  as  is  often  the 
case,  may  demand  different,  perhaps  more  difficult,  modes  of  treat- 
ment.    Oxidized  ores  are  the  easiest  to  smelt,  and  the  benefit  of 
careful  exploration  before  indulging  in  too  confident  expectations 
may  be  emphasized.     As  examples,  the  Ducktown  copper  deposits 


ON  STRUCTURAL  FEATURES  OF  MINERAL  VEINS.         39 

{see  Example  16),  the  Leadville  silver  mines  (Example  30),  the 
southwest  Virginia  zinc  deposits  at  Bonsacks  (Example  27),  the 
copper  and  silver  veins  at  Butte,  Mont.  (Example  lY),  and  others 
in  Llano  County,  Texas  (Example  I7c),  may  be  cited.  At  Duck- 
town  a  considerable  thickness  of  chalcocite,  melaconite,  and  carbon- 
ates accumulated  just  at  the  water  line  and  abruptly  changed  to 
low-grade,  unworkable  pyrite  and  chalcopyrite  below  it.  At  Bon- 
sacks,  near  Roanoke,  Ya  ,  very  rich,  easily  treated  earthy  limon- 
ite  and  smithsonite  (30-40  %  zinc)  passed  into  a  refractory,  low- 
grade  (15-20  %  zinc),  intimate  mixture  of  blende  and  pyrite. 
Excavations  in  dry  districts  may  not  reach  the  water  line  for  great 


y £(j.  7._ illustration  of  the  oxidized  zone,  or  gossan,  the  zone  of  enrich- 
ment, and  the  unchanged  sulphides,  at  Ducktown,  Tenn.    After 
A.  F.  Wendt,  School  of  Mines  Quarterly,  Vol.  VII.,  1886. 

depths.     Thus  at  Eureka,  Nev.,  in  the  rainless  region  of  the  Great 
Basin,  the  oxidized  ores  continue  to  900  feet. 

It  is  worthy  of  remark  in  this  connection  that  possibly  some 
deposits  of  oxidized  ores  may  have  been  formed  originally  as  such. 
Wendt  has  argued  this  for  the  copper  mines  of  the  Bisbee  dis- 
trict, Arizona.  (See  Example  20&.)  If  oxidized  ores  are  now 
found  below  the  water  line,  it  may  indicate  a  depression  of  the 
rocks  from  a  previous  higher  position.  R.  C.  Hills  has  brought  out 
a  very  interesting  instance  of  the  concentration  of  gold  and  silver 
in  the  lower  part  of  the  oxidized  zone,  or  at  least  at  a  considerable 
depth  below  the  outcrop.  The  upper  portion  of  the  vein,  in  this 
•case  with  a  quartz  gangue,  was  impoverished.  The  gold  is  thought 

*•'** 


40  KEMP'S   ORE  DEPOSITS. 

to  have  been  carried  down  in  solution  with  ferrous  and  ferric  sul- 
phates, which  were  decomposed  by  feldspar,  while  the  precious 
metal  was  thrown  down.  The  ore  bodies  lie  in  the  Summit  district, 
Rio  Grande  County,  Colorado.  (R.  C.  Hills,  Proc.  Colo.  Sci.  Soc., 
Vol.  I.,  p.  32  ;  S.  F.  Emmons,  quoting  Hills,  Engineering  and  Min- 
ing Journal,  June  9,  1883.) 

1.05.07.  The  waters  of  mines  which  have  opened  up  and  ex- 
posed sulphides  to  oxidation  are  often  charged  with  sulphuric  acid 
and  even  metallic  salts.     This  is  especially  true  of  mines  in  copper 
sulphides,  and  the  pumps  are  much  corroded.     In  instances  con- 
siderable metallic  copper  has  been  removed  by  passing  the  mine 
drainage  over  scrap-iron,  as  at  Ducktown,  Tenn.,  and  as  has  been 
lately  introduced  experimentally  at  Butte,  Mont.     Mine  timbers 
have  been  preserved  very  long  periods  by  the  deposition  of  copper 
on  them,  from  their  reducing  action  on  the  solutions.     Pumps  and 
timbers  placed  by  the  Romans  in  the  Rio  Tinto  mines,  in  Spain, 
are  still  in  good  preservation.     Even  gold  has  been  detected  in 
Australian  mine  waters.      (See  School  of  Mines    Quarterly,  Vol. 
XL,  p.  364,  for  review  of  literature  bearing  on  this  subject.) 

1.05.08.  Electrical  Activity. — A  theoretical  agent  for  the  pre- 
cipitation of  ores  in  veins,  which  was  a  great  favorite  among  the 
writers  fifty  or  sixty  years  ago,  was  electrical  action,  and  careful 
experiments  were  made  in  England  and  Germany  to  detect  it.    By 
connecting  the  opposite  ends  of  a  vein  with  a  wire,  in  which  was  a 
galvanometer,  the  attempt  was  made  again  and  again  to  establish 
the  existence  of  galvanic  action.     At  times  the  results  gave  some 
grounds  for  belief  ;  but  at  others  they  were  contradictory  or  un- 
certain, 'so   that   no    very   definite   or   reliable   conclusions   were 
established.     Other  experiments    were    made   in  Germany    about 
1844,  by  Reich,  while  lately  quite  elaborate  investigations  have 
been  carried  out  by  Dr.  Carl  Barns  on  the  Comstock  Lode,  and  at 
Eureka,  Nev.     Great  difficulties  are  met  in  preserving  the  neces- 
sary insulation  throughout  the  wet  and  devious  underground  work- 
ings, and  amid  such  surroundings  in  detecting  the  currents,  which 
would  be  necessarily  small.     With  Barus  the  thesis  was  not  alone 
to  establish  a  galvanic  action,  such  as  might  be  a  precipitating 
agency,  but  also  to  observe  what  effect,  if  any,  was  exerted  by  the 
intervention  of  an  ore  body  on  the  normal  terrestrial  currents. 
Had  this  latter  been  proved  of  sufficient  amount,  the  existence  of 
such  bodies  might  be  indicated  by  plotting  electrical  observations. 
While  in  some  respects  of  interest,  the  results  of  Dr.  Barus  are  not 


ON  STRUCTURAL  FEATURES  OF  MINERAL  VEINS.         41 

very  decisive,  and  this  line  of  investigation  is  hardly  to  be  con- 
sidered a  promising  one.  The  importance  attached  to  it  in  former 
years  may  be  illustrated  by  these  words  of  De  la  Beche,  one  of 
the  ablest  of  English  writers,  in  1839.  Speaking  of  veins  in  general, 
after  discussing  those  of  Cornwall  in  particular,  he  says  :  "  Mineral 
veins  result  from  the  filling  of  fissures  in  rocks  by  chemical  deposits, 
from  substances  in  solution  in  the  fissures,  such  deposits  being 
greatly  due  to  electro-chemical  agency." 


CHAPTER   VI. 

THE  CLASSIFICATION  OF  ORE  DEPOSITS,    A    REVIEW    AND    A 
SCHEME  BASED  ON  ORIGIN. 

1.06.01.  In  the  classification  of  ore  deposits  the  same  syste- 
matic arrangement  is  not  to  be  expected  as  in  the  grouping  of  plants, 
animals,  or  minerals.     Ore  deposits  have  not  the  underlying  affin- 
ities and  relationships  of  living  organisms  or  of  definite  chemical 
compounds.     The  series  of  objects  is  too  diverse,  and,  in  the  na- 
ture of  the  case,  the  standards  of  appeal  must  be  different.     The 
subject  is,  however,  one  of  great  practical  importance  as  well  as 
of  great  scientific  interest.     A  vocabulary  of  intelligible  terms  is 
indispensable  for  description  and  comparison,  and,  under  our  min- 
ing laws,  often  for  valid  titles,  while  as  a  vehicle  for  the  spread  of 
knowledge  and  reasonable  conceptions  regarding  these  phenomena, 
its  importance  cannot  be  overestimated. 

1.06.02.  All  schemes  of  classification  rest  on  these  principles  : 
form,  origin, — or  the  genetic  principle  (including  method,  relative 
time  of  origin  as  contrasted  with  the  walls,  etc.), — state  of  aggre- 
gation, and  mineral   contents.     Of  these,  the  principle  of  form  is 
usually  esteemed  the  weightiest,  and  is  given  the  greatest  promi- 
nence, partly  because  it  has  been  thought  to  be  the  one  most  close- 
ly affecting  exploitation,  and  partly  because  it  involves  less  that  is 
or  has  been,  up  to  very  recent  times,  more  or  less  hypothetical. 
Yet  form  is  largely  fortuitous,  and  it  has,  of  course,  no  law,  while, 
with  sufficient  knowledge,  the  genetic  principle  is  the  one  giving  a 
far  more  thoroughly  scientific  basis.     Every  one,  in  opening  up  or 
searching  for  an  ore  body,  must  be  influenced  by  some  hypothesis, 
either  of  shape  or  of  origin.     It  is  the  conviction  of  the  writer 
that,  with  all  our  deficiencies  of  knowledge,  the  genetic  principle 
is  also  the  best  guide,  even  in  practical  development. 

1.06.03.  Very  early  in  the  development  of  mining  literature 
the   distinction   was  made  between  those   ore  bodies   which   are 
parallel  to  the  stratification  and  those  which  break  unconformably 


CLASSIFICATION  OF  ORE  DEPOSITS.  43 

across  it.  This  took  place  long  before  the  epoch-making  time  of 
Werner,  and  even  before  the  conception  of  the  relative  ages  of 
strata  had  been  at  all  generally  grasped.  Thus  among  the  Ger- 
mans we  find  the  terms  "  Lager  "  and  "  Flotze  "  1  on  the  one  side, 
being  set  off  in  contrast  to  "  Gang  "  (vein)  on  the  other.  Werner, 
writing  in  1791,  quotes  Von  Oppel's  distinctions  between  Flotze 
(strata,  beds)  and  Gange  (veins),  which  were  published  in  1749  ; 
but  without  doubt,  as  mining  terms,  they  go  much  further  back. 
Beyond  this  simple  indication  of  the  views  of  the  older  writers,  no 
attempt  will  be  made  here  to  quote  authorities  earlier  than  1850. 
This  is  justifiable  because  the  important  works,  like  De  la  Beche's 
Geology  of  Cornwall  and  Devon,  and  Kenwood's  Metalliferous 
Deposits  of  Cornwall  and  Devon,  are  rather  discussions-  of  veins 
than  systematic  attempts  at  classification. 

In  the  following  pages  the  principal  schemes  of  classification 
are  grouped  according  to  certain  relationships  and  similarities 
that  run  through  them.  It  would  be  interesting  to  arrange  them 
in  chronological  order,  but  points  of  likeness  and  unlikeness  would 
not  be  thus  brought  out,  nor  can  the  influence  of  one  writer  on 
another  be  so  clearly  manifested.  The  underlying  object,  aside 
from  showing  in  a  bird's-eye  view  what  has  been  done,  is  to  lead 
up  to  an^attempt  at  a  purely  genetic  classification  from  which 

1  Lager  and  Flotze  are  difficult  to  render  into  English  while  retaining 
their  native  shades  of  meaning.  The  later  writers  in  Germany  (Serlo, 
Gatzschmann,  Von  Groddeck,  Kohler)  define  them  as  being  interbedded 
bodies,  each  later  than  the  foot  wall  in  formation,  and  older  than  the 
hanging  ;  and  that  Lager  are  much  more  limited  in  horizontal  extent  than 
Flotze.  E.  Wabner  shows,  however,  in  the  Berg.  u.  Huet.  Zeitung,  Jan. 
2,  1891,  p.  1,  that  writers  in  the  earlier  part  of  the  century  did  not  entirely 
restrict  the  term  Lager  as  regards  age  relative  to  the  foot  and  hanging, 
but  applied  it  to  ore  bodies,  which  follow  the  general  bedding,  although 
they  may  have  been  introduced  much  later  than  the  formation  of  the 
walls.  Thus  the  frequent  occurrence  of  lead  ores  in  limestone  along  cer- 
tain beds  (southeast  Missouri,  for  example)  would  be  called  Lager.  We 
would  apply  the  terms  impregnation,  or  dissemination,  or  bed-vein,  to 
such.  Flotz  we  would  call  stratum,  and  Lager,  as  defined  by  the  later 
authors,  "  bed  "  or  "seam."  Werner,  for  instance,  in  his  classification 
of  the  rock  formatibns  of  the  globe,  made  :  I.  Urgebirge  (Primitive,  Pri- 
mary, etc.,  having  no  fossils).  II.  Secondary,  subdivided  into  A.  Ueber- 
ganggebirge  (Transition,  more  or  less  metamorphosed  sediments,  but  fos- 
siliferous).  B.  Flotzgebirge  (Unaltered  strata).  From  this  the  meaning 
of  Flotz  can  be  grasped.  By  contrast,  a  magnetite  lense  is  a  good  illus- 
tration of  Lager. 


BNIVEBblTS 


4  4  KEMP'S   ORE  DEPOSITS. 

mere  form  is  eliminated  to  the  last  degree,  and  well-recognized 
geological  phenomena  are  brought  to  the  foreground.  It  has  in- 
deed been  said  with  force  that  the  origin  of  ore  deposits  is  a  sub- 
ject which  is  very  largely  a  matter  of  hypothesis,  and  that  it  in- 
volves profound  subterranean  causes,  of  which  we  know  but  little. 
Still,  it  is  held  that  an  acquaintance  with  what  has  been  accom- 
plished in  recent  years  by  our  best  workers,  and  a  rigid  adherence 
to  well-recognized  principles  in  geology  and  mineralogy,  especially 
as  developed  in  rock  study  (i.e.,  in  that  department  of  geology 
that  of  late  years  we  have  grown  to  call  petrography),  will  estab- 
lish much  that  cannot  be  questioned,  and  will  aid  in  differentiating 
the  cases  which  are  still  objects  of  reasonable  doubt.  It  is,  how- 
ever, true  that  among  the  subjects  on  which  human  imagination, 
often  superstitious,  has  run  to  wild  extremes,  and  on  which  cranky 
dreamers  have  exercised  their  wits,  the  origin  of  ore  deposits 
stands  out  in  particularly  strong  relief. 

1.06.04.     A.  Schemes   Involving    only    the     Classification    of 
Veins. 

(i) 

G.  A.  von  Weissenbach  1  (Gangstudien,  1850,  p.  12). 

(a)  Sedimentargange  (Sedimentary  Veins). 

(b)  Kontritionsgange  (Attrition  Veins). 

(c)  Stalactitische  oder  Infiltration sgange  (Stalactitic  or  In- 

filtration Veins). 

(d)  Plutonische  oder   Gebirgsmassengange  (Masses,   dikes, 

knobs,  bosses,  etc.,  not  necessarily  with  ores). 

(e)  Ausscheidungsgange  (Segregated  Veins). 

(f)  Erzgange  (True  or  Fissure  Veins). 

(2) 

B.  von  Cotta,  in  comments  on  Von  Weissenbach's  Scheme. 
Gangstudien,  1850,  p.  79.  According  to  the  vein 
filling. 

1.  Gesteinsgange  (Dikes). 

(a)  Not  crystalline  (Sandstone). 

(b)  Crystalline  (Granite). 

2.  Mineralgange  (Veins). 

(a)  Of  one  non-metallic  mineral. 

(b)  Of  several  non-metallic  minerals. 

3.  Erzgange.     Ore  veins. 

1  See  also  Whitney's  Metallic  Wealth  of  the  U.  S.,  1854,  p.  44. 


CLASSIFICATION  OF  ORE  DEPOSITS.  45 

(3) 

B.  von  Cotta,  idem,  p.  80.     According  to  Shape  and  Position. 
I.  Wahre,  einfache  Spaltengange  (Fissures). 

(a)  Querdurchsetzende,  Cross  fissures. 

(b)  Lagergange,  Bed  veins. 

(c)  Kliifte  (Cracks),  Adern  (Yeinlets). 
II.  Gangziige  (Linked  Veins).1 

III.  Netzgange  (Reticulated  Veins). 

IV.  Contaktgiinge  (Contact  Veins). 
V.  Lenticulargange  (Lenses). 

VI.  Stockformige  Gange  (Stocks,  Masses). 

(4) 
B.  von  Cotta,  idem,  p.  80.     According  to  the  texture  of  the 

vein  filling. 

I.  Dichte  Gange  (Compact  Veins). 
II.  Krystallinische  Gange. 

III.  Krystallinisch,  kornige  (granular)  Gange. 

IV.  Krystallinisch,  massige  (massive)  Gange. 

V.  Gange  mit  Lagentextur  (Banded  veins). 

(a)  Ohne  Symmetric  der  Lagen  (unsymmetrical). 

(b)  Mit  Symmetric  der  Lagen  (symmetrical). 
VI.  Gange  mit  Breccien  oder  Conglomerattextur. 

(5) 

J.  Leconte,  Amer.  Jour.  Sci.,  July,  1883,  p.  17. 

1.  Fissure  Veins. 

2.  Incipient  Fissures,  or  Irregular  Veins. 

3.  Breceiated  Veins. 

4.  Substitution  Veins. 

5.  Contact  Veins. 

6.  Irregular  Ore  Deposits. 

1.06.05.  In  Von  Weissenbach's  table  the  sedimentary  veins 
are  much  the  same  as  the  "  sandstone  dikes  "  which  J.  S.  Diller 
has  recently  described.  (Bull.  Geol.  Soc.  Amer.,  I.  411.)  They 
and  the  stalactitic  veins  have  small  practical  value,  although  of 
great  scientific  interest.  Under  (d),  the  stockworks  with  tin  ores 

1  Gangziige  is  happily  translated  "linked  veins,"  by  Mr.  G.  F.  Becker 
(Quicksilver  Deposits,  p.  410).  Any  attempt  to  render  the  original  by 
preserving  the  figure  of  a  flock  of  birds  or  of  a  school  of  fish,  etc.,  is,  as 
Mr.  Becker  remarks,  infelicitous,  if  not  impossible. 


46  KEMPS   ORE  DEPOSITS. 

are  the  principal  illustration  of  economic  prominence.  The  attri- 
tion veins  are  an  important  class,  and  increasing  study  has  wid- 
ened the  application  of  this  or  synonymous  terms.  Segregated 
veins  and  true  veins  are  well-known  forms.  '  In  the  comments  of 
Von  Cotta,  which  follow  Von  Weissenbach's  paper,  veins  are 
grouped  from  every  possible  standpoint,  Von  Weissenbach's 
scheme  being  taken  as  the  one  based  on  origin.  Nos.  2  and  4  have 
small  claims  to  attention.  No.  3  foreshadows  the  drift  of  many 
subsequent  writers.  The  meanings  of  the  terms  are  self-evident, 
except  perhaps  Gangzuge  (linked  veins).  This  refers  to  a  group  of 
parallel  and  more  or  less  overlapping  veins,  deposited  along  a 
series  of  openings,  evidently  of  common  origin.  It  is  a  convenient 
term. 

The  terms  used  by  Leconte  may  be  passed  without  comment 
as  being  self-evident  in  their  meaning,  except  (4)  and  (6).  The 
scheme  was  devised,  as  a  perusal  of  the  citation  will  show,  after 
the  author  had  set  forth  some  original  views  of  the  causes  which 
lead  to  the  precipitation  of  ores,  and  had  forcibly  stated  others  very 
generally  accepted.  In  the  explanatory  text  some  quite  curious  as- 
sociations are  found,  which  are  cited  by  way  of  illustration.  Thus 
under  group  (4),  stalactites,  caves,  gash  veins,  and  the  Leadville  ore 
bodies  are  considered  examples,  and  under  group  (6)  the  grouping 
together  of  beds,  igneous  masses,  and  all  other  forms  of  so-called 
irregular  deposit  is  decidedly  open  to  criticism.  This  is  the  more 
emphatic  because  the  concluding  sentences  of  the  paper  (of  whose 
general  value  and  excellence  there  can  be  no  question)  give  the  im- 
pression that  the  author  felt  he  had  cleared  up  all  the  points  in  the 
origin  of  ore  bodies  which  would  be  of  interest  or  importance  to  a 
purely  scientific  investigator  as  contrasted  with  a  practical  miner. 

1.06.06.     B.  General  Schemes  Based  on  Form, 

(6) 

Von  Cotta  and  Prime.      Ore  Deposits,  New  York,  1870. 
I.  Regular  Deposits. 

A.  Beds. 

B.  Veins. 

(a)  True  (Fissure)  Veins. 

(b)  Bedded  Veins. 

(c)  Contact  Veins. 

(d)  Lenticular  Veins. 
II.  Irregular  Deposits. 


CLASSIFICATION  OF  ORE  DEPOSITS.  47 

C.  Segregations. 

(a)  Recumbent. 

(b)  Vertical. 

D.  Impregnations  (Disseminations). 

(?) 

Lottner-Serlo,  Leitfaden  zur  Bergbaukunde,  1869. 

I.  Eingelagerte  Lagerstatten  (Inclosed  Deposits). 

A.  Plattenformige  (Tabular). 

(a)  Gange  (Veins). 

(b)  Flotze  und  Lager  (Strata,  beds,  seams). 

B.  Massige  Lagerstatten  (Massive  Deposits). 

(a)  Stocke  )  ™ 

(V  Stockwerke  [Masses- 

C.  Andere  unregelmassige  Lagerstatten  (other  irregu- 

lar deposits). 

(a)  Nester  (Pockets). 

(b)  Putzen. 

(c)  Nieren  (Kidneys). 

II.  Aufgelagerte  Lagerstatten  (Superficial  Deposits). 

D.  Trummerlagerstatten  (Placers). 

E.  Oberflachliche  Lager  (Surface  beds). 

(8) 
Koehler,  Lehrbuch  der  Bergbaitkunde,  1887. 

I.  Plattenformige  Lagerstatten  (Tabular  Deposits). 

(a)  Gange  (Veins). 

(b)  Flotze  und  Lager  (Strata,  beds,  seams). 

II.  Lagerstatten  von  unregelmassige  Form  (Deposits  of 
irregular  Form). 

(a)  Stocke  und  Stockwerke  (Masses). 

(b)  Butzen,    ISTester,   und   Nieren  (Pockets,  concre- 

tions, etc.). 

(9) 
Gallon,   lectures   on  Mining,    1866    (Foster  and    Galloway's 

translation). 
I.  Veins. 
II.  Beds. 
III.  Masses  (i.e.,  not  relatively  long,  broad,  and  thin). 

1.06.07.     The  scheme  of  Von  Cotta  and  Prime  carries  out  the- 
principle  of  form  to  its  logical  and  somewhat  trivial  conclusion. 


48  KEMP'S  ORE  DEPOSITS. 

Thus  under  irregular  deposits  it  is  a  matter  of  extremely  small 
classificatory  moment  whether  an  ore  body  is  recumbent  or  vertical. 
Otherwise  the  scheme  is  excellent,  and  its  influence  can  be  traced 
through  most  of  those  that  are  of  later  date.  The  original  draft 
came  out  in  the  German  in  1859.  All  the  others  are  from  treatises 
on  mining,  in  which  this  subject  plays  a  minor  role,  and  indicates 
the  tendency,  referred  to  above,  of  mining  engineers,  when  writing 
theoretically,  to  imagine  certain  fairly  definite  forms,  which  are  to 
be  exploited.  As  previously  remarked,  however,  considering  the 
uncertainty  of  ore  bodies  and  their  variability  in  shape,  it  is  here 
argued  that  the  genetic  principle  might  better  take  precedence. 
Several  of  the  German  terms  are  difficult  to  render  into  English 
mining  idioms,  as  for  example,  Stock,  Butzen  (Putzen),  Nester,  and 
Nieren. 

1.06.08.     C.  Schemes,  Partly  Based  on  form,  Partly  on  Origin. 

(10) 

J..  D.Whitney,  Metallic  Wealth,  1854. 

I.  Superficial. 
II.  Stratified. 

(a)  Constituting    the  mass  of    a  bed  or   stratified 

deposit. 

(b)  Disseminated  through  sedimentary  beds. 

(c)  Originally    deposited    from   aqueous     solution, 

but  since  metamorphosed. 
III.  Unstratified. 

A.  Irregular. 

(a)  Masses  of  eruptive  origin. 

(b)  Disseminated  in  eruptive  rocks. 

(c)  Stockwork  deposits. 

(d)  Contact  deposits. 

(e)  Fahlbands. 

B.  Regular.      . 

(/)  Segregated  veins. 

(g)  Gash  veins. 

(h)  True  or  fissure  veins. 


J.  S.  Newberry,   School  of  Mines    Quarterly,   March,  1880, 

May,  1884 
I.  Superficial. 


CLASSIFICATION  OF  ORE  DEPOSITS.  49 

II.  Stratified. 

(a)  Forming  entire  strata. 

(b)  Disseminated  through  strata. 

(c)  Segregated  from  strata. 
III.  Unstratified. 

(a)  Eruptive  masses. 

(b)  Disseminated  through  eruptive  rock. 

(c)  Contact  deposits. 

(d)  Stockworks. 

(e)  Fahlbands. 
(/)  Chambers. 
(g)  Mineral  veins. 

1.  Gash  veins. 

2.  Segregated  veius. 

3.  Bedded  veins. 

4.  Fissure  veins. 

(12) 

J.  A.  Phillips,  Ore  Deposits,  1884. 
I.  Superficial. 

(a)  By  mechanical  action  of  water. 

(b)  By  chemical  action. 
II.  Stratified. 

(a)  Deposits  constituting  the  bulk  of  metalliferous 

beds  formed  by  precipitation  from  aqueous 
solution. 

(b)  Beds  originally  deposited  from  solution  but  sub- 

sequently altered  by  metamorphism. 

(c)  Ores  disseminated  through  sedimentary  beds,  in 

which  they  have  been  chemically  deposited. 
III.  Unstratified. 

(a)  True  veins. 

(b)  Segregated  veins. 

(c)  Gash  veins. 

(d)  Impregnations. 

(e)  Stockworks. 
(/)  Fahlbands. 

(g)  Contact  deposits. 
(h)  Chambers  or  pockets. 

1.06.09.  It  is  at  once  apparent  that  Whitney's  scheme  contains 
the  essentials  of  the  others,  which  are  merely  slight  modifications. 
Xewberry  introduces  impregnations,  chambers,  and  bedded  veins. 


50  KEMP'S   ORE  DEPOSITS. 

The  first  named  is  a  useful  term,  although  it  is  not  always  easy  to- 
distinguish  impregnations  from  others  earlier  given.  Thus,  they 
may  be  very  like  the  division,  disseminated  through  strata,  or  dis- 
seminated through  eruptive  rock,  or,  if  in  metamorphic  rock,  f  ahl- 
bands.  The  word  is  also  used  to  indicate  places  along  a  vein 
where  the  ore  has  spread  into  the  walls.  The  term  "  chambers,'* 
or  "  caves,"  has  found  application  in  the  West,  and  is  a  useful  ad- 
dition. Bedded  veins  appear  also  in  Yon  Cotta  above  (No.  6). 
Phillips  seeks  to  explain  the  methods  of  origin  in  his  use  of  Whit- 
ney's scheme  and  clearly  feels  the  importance  of  emphasizing  the 
genetic  principle  more  strongly.  Much  of  it  is  implied  in  the 
simpler  phraseology,  however,  and  the  extended  sentences  lack  the 
incisiveness  of  the  earlier  schemes.  The  arrangement  as  set  forth 
by  Whitney  is  worthy  of  high  praise,  and  the  scheme  is  one  of 
the  many  valuable  things  in  a  book  that  has  played  a  large  part  in 
the  economic  history  of  the  United  States. 

1.06.10.     ~D.  Schemes  Largely  Based  on  Origin. 

(13) 
J.  Grimm,  Lagerstatten,  1869. 

I.  Gemengtheile  oder  grossere  Einschliisse  in  den 
Gebirgsgesteinen.  Einsprengung,  Impregnation. 
(Essential  component  minerals  and  inclusions  in 
country  rock.  Impregnations.) 

(a)  Urspriingliche  Einsprengung.     (Original   with 

the  inclosing  rock.) 

(b)  Von  anderen  Lagerstatten  weggef  iihrte  Bruch- 

theile,  etc.  (Fragments  brought  from  a  dis- 
tance. Placers,  ore-bearing  boulders.  Brec- 
cias.) 

II.  Untergeordnete  Gebirgsglieder  oder  besondere  Lager- 
statten. (Subordinate  terranes  or  special  forms 
of  Deposits.) 

(a)  Plattenformige  Massen.     (Tabular  masses.) 

1.  Lager   oder  Flotze.      Bodensatzbildung. 

(Beds,  strata.) 

2.  Gange,  Kliifte,  Gangtrummer,  etc.  (Veins 

of  varying  sizes.) 

3.  Plattenformige  Erz-ausscheidungen    und 

Anhaufungen.     (Segregated  veins.) 

(b)  Stocke  und  regellos  gestaltete  Massen.     (Stocks 

and  irregular  masses.) 


CLASSIFICATION  OF  ORE  DEPOSITS.  51 

1.  Lagerstocke  Linsenstocke,  Linsen.     (Len- 

ticular deposits,  etc.) 

2.  Stocke,    Butzen,    Nester,    etc.     (Masses, 

pockets,  etc.) 

3.  Stockwerke.     (Stockworks.) 

(14) 

A.  von  Groddeck,  Lehre  von  den  Lagerstatten,  etc.,  1879,  p.  84. 
I.  Ursprungliche  Lagerstatten  (Primary  deposits). 

A.  Gleichzeitig  mit  dem  Nebengestein  gebildet. 

(Formed  at  the  same  time  with  the  walls.) 

1.  Geschichtete.     (Stratified.) 

(a)  Derbe  Erzflotze.     (Entire  beds  in  fossiliferous 

strata.) 

(b)  Ausscheidungsflotze.     (Disseminated  in  beds.) 

(c)  Erzlager.     (Lenticular  beds,  mostly  in  schists.) 

2.  Massige.     (Massive;  the  word   is  nearly 

synonymous  with  igneous.) 

B.  Spater  wie  das  Nebengestein  gebildet.     (Formed 

later  than  the  walls.) 

3.  Hohlraumsfullungen.     (Cavity  fillings.) 

(a)  Spaltenfiillungen  oder  Gauge.    (Fissure  fillings 

or  veins.) 

(1)  In  massigen  Gesteinen.  (In  igneous  rocks.) 

(2)  In  geschichteten  Gesteinen.     (In  strati- 

fied rocks.) 

(b)  Hohlenfiillungen.    (Chambers.) 

4.  Metamorphische   Lagerstatten.     (Altera- 

tions, replacements,  etc.) 
II.  Triimmer-lagerstatten.  (Secondary  or  detrital  deposits.) 

(15) 

R.  Pumpeliy,  Johnson's  Encyclopaedia,  1886,  VI.  22. 
I.  Disseminated     concentra- 
tion. 


(a)  Impregnations, 


Fahlbands.  .,    .,       .     ,     . 

TT    .  ,  „  .  ure    of    the   inclosing 

II.  Aggregated  Concentration.  .  . 

3°   .&T       .  [-      rock,  or  to  its  mineral 

(a)  Lenticular  aecgrega-  ^.,    ,.  ,     , 

v  '     .  TIT  constitution,  or  to  both 

tions  and  beds. 

/lx  T          .  causes. 

(0)  Irregular  masses. 

(c)  Reticulated  veins. 

(d)  Contact  deposits. 


Forms  due  to  the   text- 


52  KEMP'S  ORE  DEPOSITS. 

III.  Cave  deposits.  \  Forms  chiefly  due  to  pre- 

IV.  Gash  veins.  v      existing  open   cavities 
V.  Fissure  veins.                         )       or  fissures. 

VI.  Surface  deposits. 

(a)  Residuary  deposits. 

(b)  Stream  deposits. 

(c)  Lake  or  bog  deposits. 

1.06.11.  These  three  are  all  excellent,  and  give  some  interest- 
ing variations  in  the  several  points  of  view  from  which  each  writer 
regarded  his  subject.     There  are  instances  in  the   two  German 
schemes  where  it  is  difficult  to  render  the  original  into  a  corre- 
sponding English  term  and  recourse  has  been  had  to  the  explana- 
tory text.     Grimm  especially  writes  an  obscure  style.     He  divides 
accordingly  as  the  ore  forms  an  essential  and  integral  part  of  the 
walls  or  a  distinct  body.     Von  Groddeck  has  in  view  the  relative 
time  of  formation  as  contrasted  with  the  walls,    Grimm  afterward 
emphasizes  geometrical  shape,  but  this  Von  Groddeck  practically 
does  away  with,  and  continues   more  consistently  genetic.      His 
scheme  might  perhaps  come  more  appropriately  in  the  next  section. 

Pumpelly's  conception  varies  considerably  from  the  others.  He 
writes,  as  his  full  paper  states,  in  the  belief  that  the  metals  have 
all  been  derived  primarily  from  the  ocean,  whence  they  have 
passed  into  sedimentary,  and,  by  fusion  of  sediments,  into  igne- 
ous rocks.  The  group  of  residuary  surface  deposits,  carrying  out 
as  it  does  a  favorite  idea  of  Professor  Pumpelly,  as  set  forth  in 
his  papers  on  the  secular  decay  of  rocks,  is  an  important  distinction. 

1.06.12.  E.  Schemes  Entirely  J3ased  on  Origin. 

(16) 
H.  S.  Munroe.     Used  in  the  Lectures  on  Mining  in  the  School 

of  Mines,  Columbia  College. 
I.  Of  surface  origin,  beds. 

(a)  Mechanical  (action  of  moving  water). 

1.  Placers  and  beach  deposits. 

(b)  Chemical  (deposited  in  still  water). 

1.  By  evaporation  (salt,  gypsum,  etc.). 

2.  By  precipitation  (bog  ores). 

3.  Residual  deposits  from  solution  of  lime- 

stone, etc.  (hematites). 

(c)  Organic. 

1.  Vegetable  (coal,  etc.). 


CLASSIFICATION  OF  ORE  DEPOSITS.  53 

2.  Animal  (limestone,  etc.). 
(d)  Complex  (cannel  coal,  bog  ores,  etc.). 
II.  Of  subterranean  origin. 

(a)  Filling  fissures  and  cavities  formed  mechani- 

cally. 

1.  Fissure  veins,  lodes. 

2.  Cave  deposits — lead,  silver,  iron  ores. 

3.  Gash  veins.     The  cavities  of  2  and  3  are 

enlarged  by  solution  of  limestone. 

(b)  Filling  interstitial  spaces  and  replacing  the  walls. 

1.  Impregnated  beds. 

2.  Fahlbands. 

3.  Stockworks. 

4.  Bonanzas. 

5.  Masses. 

1.06.13.  This   scheme   covers   all  forms  of  mineral  deposits, 
whether  metalliferous  or  not,  while  most  of  those  previously  given, 
as  well  as  the  one  that  follows,  concern  only  metalliferous  bod- 
ies.    The  scheme  is  consistently  genetic  and  was  elaborated  be- 
cause such  a  one  filled  its  place   in  lectures  on  mining  better  than 
one  based  on  form.     The  general  principle  on  which  the  main  sub- 
division is  made  differs  materially  from  any  hitherto  given.     De- 
posits formed  on  the  surface  are  kept  distinct  from  those  originat- 
ing below,  even  though  the  first  class  may  afterward  be  buried. 

(17) 

1.06.14.  J.  F.  Kemp,  1892.    Revised  from  the  School  .of  Mines 
Quarterly,  November,  1892. 

I.  Of  Igneous  Origin.  Excessively  basic  developments 
of  fused  and  cooling  magmas.  Peridotite,  forming 
iron  ore  at  Cumberland  Hill,  R.  I.1  Magnetite,  Jacu- 
piranga,  Brazil.2  Titaniferous  magnetite  in  Min- 
nesota gabbros 3 ;  in  Adirondack  gabbros  * ;  in  Swe- 
dish and  Norwegian  gabbros.5 

1  M.  E.  Wadsworth,  Bull  Mus.  Comp.  Zool.,  1880,  VII. 

2  O.  A.  Derby,  Amer.  Jour.  Sci. ,  April,  1891. 

3  N.  H.  Winchell,  Tenth  Ann.  Rep.  Minn.  Geol.  Survey,  pp.  80-83. 
Bull.  VI.  of  same  Survey,  p.  135. 

4  Forthcoming  paper  by  J.  F.  Kemp. 

5  J.  H.  L.  Vogt,  Geol.  Foren.  i.  Stockholm-Forhand,  XIII.  476,  May, 
1891.    English  abstract  and  review  by  J.  J.  H.  Teall.     Geol.  Mag.,  Febru- 
ary, 1892.    See  also  Zeitschr.  fur  Praktische  Geologie,  I.  4. 


54  KEMPS  ORE  DEPOSITS. 

II.  Deposited  from  Solution. 

1.  Surface  precipitations,  often  forming  beds, 

and  caused  by — 

(a)  Oxidation.      Bog  ores.    Ferruginous  oolites,  as 

in  some  Clinton  ores.1 

(b)  Sulphurous  exhalations  from  decaying  organic 

matter  etc.     (Pyrite.) 

(c)  Reduction,    chiefly    by    carbonaceous,   organic 

matter.     (Pyrite  from  ferrous  sulphate.) 

(d)  Evaporation,    cooling,    loss   of    pressure,    etc. 

(Hot  spring  deposits,  as  at  Steamboat 
Springs,  Nev.2) 

(e)  Secretions  of  living  organisms.     (Iron  ores  by 

algae.3) 

NOTE. — These  same  causes  of  precipitation  operate  in  subter- 
ranean cavities,  although  not  again  specially  referred  to. 

2.  Disseminations    (impregnations)    in   par- 

ticular beds  or  sheets,  because  of: — 

(a)  Selective  porosity.     (Silver  Cliff,  Colo.,  silver 

ore  in  porous  rhyolite.4  Amygdaloidal  fill- 
ings, as  in  copper-bearing  amygdaloids, 
Keweenaw  Point,  Santa  Rita,  N.  M.5  Im- 
pregnations of  porous  sandstone,  as  at  Silver 
Reef,  Utah.6 

(b)  Selective  precipitation  by  limestone.     (Lateral 

enlargements  at  Newman  Hill,  near  Rico, 
Colo.7) 

3.  Filling  joints,  caused  by  cooling  or  drying. 

(Mississippi  Valley  gash  veins  in  part.) 

4.  Occupying  chambers  (caves)  in  limestone. 

(Cave  Mine,  Utah.8) 

1  C.  H.  Smyth,  Jr.,  Amer.  Jour.  Sci.,  June,  1892,  p.  487. 

2  G.  F.  Becker,  Monograph  XIII. ,  U.S.  Oeol.  Survey,  pp.  331,  468; 
Laur,  Ann.  des  Mines,  1863,  p.  421;  J.  Leconte,  Amer.  Jour.  Sci.,  June, 
1883,  p.  424,  July,  p.  1;  W.  H.  Weed,  idem,  August,  1891,  p.  166. 

8  Sjogrun,  Berg.-  und  Hutt.  Zeit.,  1865,  p.  116. 

4  Clark,  Engineering  and  Mining  Journal,  Nov.  2,  1878,  p.  314. 

5  A.  F.  Wendt,  Trans.  Amer.  Instit.  Min.  Eng.,  XV.  27. 

6  C.  M.  Rolker,  idem,  IX.  21. 

7  J.  B.  Farish,  Proc.  Colo.  Sci.  Soc.,  April  4,  1892. 

8  J.  S.  Newberry,  School  of  Mines  Quarterly,  March,  1880.     See  also 
J.  P.  Kimball,on  Santa  Eulalia,  Chihuahua,  Amer.  Jour.  Sci.,  II.,  xlix.  161. 


CLASSIFICATION  OF  ORE  DEPOSITS.  55 

5.  Occupying   collapsed    (brecciated)    beds, 

caused  by  solution  and  removal  of  sup- 
port, or  from  dolomitization  of  limestone. 
(Southwest  Missouri  zinc  deposits.1) 

6.  Occupying  cracks  at   Monoclinal  bends, 

Anticlinal  summits,  Synclinal  troughs, 
often  with  replacement  of  walls.  (Gash 
veins  in  part  ;  galena  deposits  at  Mine 
la  Motte,  Missouri ;  zincblende  deposits 
in  the  Saucon  Valley,  Pennsylvania.3 

7.  Occupying   Shear-zones,   or   dynamically 

crushed  strips  along  faults,  whose  dis- 
placement may  be  slight,  closely  re- 
lated to  No.  8.  (Butte,  Mont.*) 

8.  True  veins  filling  an  extended  fissure,  often 

with  lateral  enlargements.  See  also  un- 
der 5. 

9.  Occupying  Volcanic   necks,    in    agglom- 

erates. (Bassick  and  Bull  Domingo 
Mines,  near  Rosita,  Colo.5) 

10.  Contact  deposits.  Igneous  rocks  almost  al- 

ways form  one  wall.  Fumaroles.  (Mar- 
quette  hematites,  Michigan.6  Greisen.) 

11.  Segregations  formed  in  the  alteration  of 
igneous  rock.     (Chromite  in  serpentine.) 

III.  Deposited  from  Suspension. 

1.  Metalliferous  Sands  and  Gravels,  whether 

now  on  the  surface  (placers,  magnetite 
beach-sands),  or  subsequently  buried. 
(Deep  gravels,  magnetite  lenses  ?) 

2.  Residual     Concentrations,     left    by   the 

weathering  of  the  matrix.  (Iron  Moun- 
tain, Mo.,  hematite  in  part.7) 

1  F.  L.  Clerc,  Lead  arfd-Zirtc-Ores  in  Southwest  Missouri  Mines, 
Carthage,  Mo.,  1887;  A.  Schmidt,  Missouri  Geol.  Survey,  1874,  p.  384. 

2  T.  C.  Chamberlain,  Wis.  Geol.  Survey,  IV.,  1882,  367. 

8  F.  L.  Clerc,  Mineral  Resources,  1882,  p.  361;  H.  S.  Drinker,  Trans. 
Amer.  Inst.  Min.  Eng.,  I.  367. 

4  S.  F.  Emmons,  Trans.  Amer.  Inst.  Min.  Eng.,  XVI.  49;  W.  P.  Blake, 
idem,  XVI.  65. 

6  C.  W.  Cross,  Proc.  Colo.  Sci.  Soc.,  1890,  p.  269. 

6  C.  R.  Van  Hise,  Amer.  Jour.  Sci  ,  February,  1892,  p.  116. 

7  R.  Pumpelly,  Bull.  Geol.  Soc.  Amer.,  II.,  p.  220. 


56  KEMPS   ORE  DEPOSITS. 

1.06.15.  It  is  believed  that  under  the  above  heads  are  included 
all  the  forms  of  ore  bodies  which  constitute  well-recognized   and 
fairly  well  understood  geological  phenomena.     To  these  catego- 
ries year  by  year  we  are  enabled,  by  the  results  of  extended  and 
careful  investigation,  to  refer  many  that  have  been  obscure.     A 
number  of  familiar  terms  for  ore  bodies  in  mining  literature  fail 
to  appear,  but  are  mentioned  in  the  classifications  quoted   from 
others.     Many  of  these  refer  only  to  form,  and  geologically  con- 
sidered are  only  convenient  admissions  of  ignorance  as  to  origin. 
Some  other  ore  bodies  whose  methods  of  origin  are  involved  in  the 
processes   of   regional   metamorphism   are   placed   by   themselves 
farther  on.    The  explanations  of  them  are  as  yet  hypothetical.     A 
few  comments  on  the  scheme  may  now  be  added,  although  in  the 
main  it  explains  itself. 

1.06.16.  I.     Much  attention  has  been  given  of  late  years*  to 
processes  of  rock  formation  from  igneous  magmas.     Of  these  the 
excessively  basic  are  the  only  ones  primarily  concerned  with  ores. 
It  is  well  known  that  in  the  series  of  igneous  rocks  we  have  suc- 
cessively those  with  less  and  less  silica.     It  is  quite  conceivable 
that  local  developments  might  bring  about  such  a  decrease  of  the 
silica  and  such  an  increase  of  one  of  the  commonest  of  the  bases, 
iron  oxide,  that  the  limits  of  an  ore  might  be  reached.     Such  bod- 
ies are  almost  always  highly  titaniferous,  so  much  so  that  in  this 
country  they  are  not  available.     Not  a  little  attention  was  direct- 
ed in  earlier  years   to  the  Cumberland   Hill   outcrop   in    Rhode 
Island,  but  it  was  found  to  be  too  high  in  this  element  to  be  suited 
to  furnace  practice.     No  analyses  are  at  hand  of  the  Brazilian  ex- 
ample,  but   a  considerable  percentage  of  titanium  might  be  ex- 
pected.    The  presence  of  these  ores  in  Canada,  the  Adirondacks, 
and  Minnesota   is  very  familiar.     It  is  possible,  as   indicated  by 
Yogt,  that  when  magnetite  crystals  had  formed  in  the  still  fused 
magma,  they  became  aggregated   by  magnetic   currents   in   the 
earth.     And  it  is   also   conceivable  that  these  early  and   heavy 
crystallizations  may  have  settled  to  the  lower  portions  of  the  mag- 
ma aiid  have  become  concentrated.     Much  that  is  more  or  less 
speculative  is  involved  in  these  explanations. 

1.06.17.  Under  II.     1,    the   precipitating  agencies    are    men- 
tioned, which  are  the  chief  causes  in  the  chemical  reactions  of  de- 
position, and  these  run  through  all  the  subterranean  cavities  as 
well.      The   general   application   is   esteemed   self-evident.      The 
large  part  played  by  organic  matter,  both  when  living  and  when 


CLASSIFICATION  OF  ORE  DEPOSITS.  57 

dead  and  decaying,  is  notable.  Its  office  even  in  precipitating  the 
gangue  minerals  in  surface  reactions  we  are  just  beginning  to 
appreciate.  Siliceous  sinters  have  been  shown  by  W.  H.  Weed  to 
be  formed  around  the  hot  springs  of  the  Yellowstone  Park  through 
the  agency  of  algae,  and  A.  Rotbpletz  has  recently  proved  that  the 
calcareous  oolites  around  the  Great  Salt  Lake  are  referable  to  mi- 
nute organisms.  Many  accumulations  of  iron  ores  have,  with  reason, 
been  attributed  to  the  same  agency;  but  for  this  metal  ordinary 
and  common  chemical  reactions  are  oftenest  applicable.  When  or- 
ganic matter  decays,  sulphurous  gases  are  one  of  the  commonest 
products,  and  likewise  one  of  the  most  vigorous  of  precipitants. 
Thus  under  Example  24,  Paragraph  2.06.03,  when  speaking  of  the 
Wisconsin  zinc  and  le^d  mines,  it  will  be  seen  that  such  an  agency 
from  decaying  seaweeds  has  been  cited  by  both  Whitney  and 
Chamberlain.  When  the  products  of  such  decomposition  become 
imprisoned  in  the  rocks  as  oils  and  gases,  their  action  is  unmistak- 
ably important  and  is  especially  available  in  limestones.  Organic 
matter  is  a  powerful  reducing  agent  as  well,  and  in  this  way  is  ca- 
pable of  bringing  down  metallic  compounds.  The  silver-bearing 
sandstones  of  southern  Utah  are  cases  in  point,  as  they  afford  plant 
impressions  now  coated  with  argentite.  The  purely  physical  agen- 
cies cited  under  (cl)  have  also  an  important  role. 

1.06.18.  Under  2  (a)  the  uprising  solutions  may  be  diverted  by 
porous  strata  so  as  to  soak  through  them  and  become  subject  to 
precipitating  agents  of  one  kind  or  another.     They  furnish  the 
simplest  kind  of  cavities,  and  starting  with  these  the  scheme  is  de- 
veloped in  a  crescendo  to  the  most  complicated.    The  purely  chem- 
ical action  of  limestone  beds,  however,  seems  at  times  to  come  into 
play  and  to  cause  precipitation  along  them.     Of  all  rocks  they  are 
the  most  active  chemical  reagent.     It  may  be  questioned  with  rea- 
son as  to  whether  caves  or  caverns  (4),  properly  so  called,  have  ever 
formed  a  resting-place  for  ores.     So  many  which  have  been  cited  as 
such  may  with  greater  reason  be  referred  to  shrunken  replacements 
that  a  doubt  hangs  over  their  character. 

1.06.19.  Under  (5)  brecciated  beds  whose  fragments  are  coat- 
ed and  whose  interstices  are  filled  with  ore  are,  with  great  reason, 
referred  to  the  collapse  from  the  removal  of  a  supporting  layer.    In 
addition  to  the  illustration  cited,  the  red  hematite  deposits  of  Dade 
and  Crawford  counties,  Missouri,  have  been  thought  to  have  had  a 
similar  origin.     Such  phenomena  are  only  to  be  expected  in  regions 
that  have  long  been  land.     Cracks  at  the  bends  of  folds  may,  in 


58  KEMP'S  ORE  DEPOSITS. 

<?ases,  have  occasioned  impregnations  and  disseminations,  even  when 
their  character  is  obscured.  The  cracks  need  be  but  small  and  nu- 
merous to  have  occasioned  far-reaching  results.  If  a  fault  fissure, 
as  a  possible  conduit  of  supply,  crosses  the  axis  of  the  fold,  the 
necessary  conditions  are  afforded  for  extended  horizontal  enrich- 
ment. Recent  explorations  with  the  diamond  drill  at  Mine  la  Motte 
seem  to  corroborate  such  an  hypothesis.  Should  the  anticline 
or  roll  afterward  sink  toward  the  horizontal,  a  very  puzzling  de- 
posit might  originate.  Shear  zones  have  been  already  discussed  at 
length  (1.02.03),  as  have  true  veins  and  volcanic  necks  (see  also 
2.09.20).  As  regards  contact  deposits,  the  igneous  rock,  which 
usually  forms  one  wall,  may  serve  two  different  purposes.  It  may 
act  merely  as  an  impervious  barrier  which  directs  solutions  along  its 
course,  or  serves  to  hold  them,  either  because  it  is  itself  bent  into 
a  basin-like  fold,  or  because  it  forms  a  trough  with  a  dense  bed 
dipping  in  an  opposite  direction.  Such  relations  occur  in  the  Mar- 
quette  and  Gogebic  ranges  of  the  Lake  Superior  iron  region.  It  is 
not  apparent  that  in  these  cases  the  igneous  rock  has  in  any  degree 
stimulated  circulations.  In  the  more  characteristic  "  contact  depos- 
its "  the  igneous  rock  has  apparently  been  a  strong  stimulator  of 
ore-bearing  circulations,  and  often  the  source  of  the  metals  them- 
selves. This  form  of  deposit  becomes,  then,  an  attendant  phenom- 
enon, or  even  a  variety,  of  contact  metamorphism.  Under  11 
chromite  is  the  chief  illustration.  The  mineral  is  practically  limit- 
ed to  serpentinous  rocks,  and  is  distributed  through  them  in  irreg- 
ular masses.  It  appears  to  be  an  auxiliary  product  of  alteration. 

1.06.20.  III.  The  debris  that  results  from  the  weathering  of 
rock  masses  under  the  action  of  frost,  wind,  rain,  heat,  and  cold  is 
washed  along  by  the  drainage  system  of  a  district,  and  the  well- 
known  sorting  action  transpires,  which  is  so  important  in  connec- 
"•;on  with  the  formation  of  the  sedimentary  rocks.  Minerals  of 
great  specific  gravity  tend  to  concentrate  by  themselves,  while 
lighter  materials  are  washed  farther  from  the  starting  point,  and 
settle  only  in  still  water.  Stream  bottoms  supply  the  most  favor- 
able situations,  and  in  their  bars  are  found  accumulations  of  the 
heavier  minerals  which  are  in  the  surrounding  rocks.  The  com- 
monest of  these  are  magnetite,  garnet,  ilmenite,  wolframite,  zircon, 
topaz,  spinel,  etc.,  and  with  these,  in  some  regions,  native  gold, 
platinum, iridosmine,  etc.;  in  other  places  cassiterite,  or  stream  tin, 
as  described  under  tin.  Even  an  extremely  rare  mineral  such  as 
monazite  may  make  a  sandbar  of  considerable  size.  (See  O.  A. 


CLASSIFICATION  OF  ORE  DEPOSITS.  59 

Derby,  Amer.  Jour.  Sci.9  III.  xxxvii.,  p.  109.)  The  action  of  surf 
or  smaller  shore  waves  is  also  a  favorable  agent.  The  throw  of  the 
breaker  tends  to  cast  the  heavier  material  on  the  beach,  where  its 
greater  specific  gravity  may  hold  it  stationary.  The  heavier  min- 
erals may  be  sorted  out  of  a  great  amount  of  beach  sand.  Mag- 
netite sands,  which  have  accumulated  in  this  way,  are  of  quite 
wide  distribution,  and  at  present  are  of  some  though  not  great 
importance.  (Example  15.)  With  the  magnetite  are  found  grains 
of  garnet,  hornblende,  augite,  etc.,  and  often  ilmenite.  Gold  is 
concentrated  in  the  same  way  along  the  Pacific  by  the  wash  of 
surf  against  gravel  cliffs.  In  abandoned  beaches  of  Lake  Bonne- 
ville,  near  Fish  Springs,  Tooele  County,  Utah,  placers  of  rolled 
boulders  of  argentiferous  galena  have  been  worked. 

A  superficial  deposit  of  somewhat  different  origin  is  the  bed  of 
hematite  fragments  that  mantles  the  flanks  of  Iron  Mountain,  Mis- 
souri, and  runs  underneath  the  Cambro-Silurian  sandstones  and 
limestones.  This  seems  to  have  been  formed  by  the  subaerial  decay 
of  the  inclosing  porphyry.  The  heavier  specular  ore  has  thus  been 
concentrated  by  its  greater  specific  gravity  and  resistant  powers. 
(See  R.  Pumpelly,  "  The  Secular  Disintegration  of  Rocks,"  Proc* 
Geol  Soc.  Amer.,  Vol.  II.,  December,  1890.) 

1.06.21.  There  remain  a  few  of  great  importance,  but  whose 
geological  history  is  less  clearly  understood.  They  are  nearly  all 
involved  in  processes  of  regional  metamorphism,  and  therefore  in 
some  of  the  most  difficult  problems  of  the  science.  Lenticular  beds 
or  veins  of  magnetite  and  pyrite  that  are  interbedded  with  schists, 
slates,  or  gneisses  are  the  principal  group.  Such  magnetite  bodies 
have  been  regarded  as  intruded  dikes,  as  original  bodies  of  bog  ore 
in  sediments  which  have  later  become  metamorphosed,  and  as. 
concentrated  delta,  river,  or  beach  magnetite  sands.  It  is  possible 
that  in  instances  they  may  be  replaced  bodies  of  limestone,  after- 
ward metamorphosed.  The  lenticular  shape  and  the  frequent  over- 
lapping arrangement  of  the  feathering  edges  in  the  foot  wall  are 
striking  phenomena. 

The  overlap  was  referred  by  H.  S.  Munroe  in  the  School  of 
Mines  Quarterly,  Vol.  III.,  p.  34,  to  stream  action  during  mechanical 
deposition,  and  a  figure  of  some  hematite  lenses  in  the  Marquette 
region  was  given  in  illustration.  The  arrangement  in  instances 
also  suggests  the  shearing  and  buckling  processes  of  dynamic  meta- 
morphism and  disturbance.  The  individual  lenses,  now  in  linear 
series,  were  thus  all  one  original  bed.  The  crumpling  of  the 


60  KEMPS   ORE  DEPOSITS. 

schistose  rocks  has  pinched  them  by  small  buckling  folds  and 
shoved  the  ends  slightly  past  each  other  in  the  process  so  familiar 
in  the  production  of  reversed  faults  from  monoclines.  Sheared 
granitic  veins  on  a  small  scale  are  a  not  uncommon  thing  in  areas  of 
schistose  rocks,  such  as  Manhattan  Island,  in  the  city  limits  of 
New  York,  and  suggest  strongly  this  explanation.  Should  the 
compression  not  go  so  far  as  to  bring  rupture  of  the  bed,  but  only 
a  thickening  by  the  formation  of  a  sigmoid  fold,  it  would  occasion 
an  enlarged  cross  section,  as  has  been  suggested  by  B.  T.  Putnam 
(Tenth  Census,  Vol.  XV.  110)  for  the  great  magnetite  ore  body 
at  Mine  21,  Mineville,  in  the  Lake  Champlain  region. 

1.06.22.  Quartz  veins,    often  auriferous  and  of  a  lenticular 
character,  furnish  another  puzzling  ore  body.    They  are  commonly 
called  segregated  veins,  and  lie  interbedded  in  slates  or  schistose 
rocks.     If  in  a  pre-existing    cavity,   it  must  have  been  formed, 
either  by  the  opening  of  beds  under  compression,  or  by  displace- 
ment along  the  bedding,  so  that  depressions  came  opposite  each 
other.     Replaced  lenses  of  limestone  which  had  been  squeezed  into 
this  shape  from  an  original,  connected  bed  should  also  be  instanced 
as  a  possibility.     The  name  "  segregated  "  would  imply  a  filling 
by  lateral  secretion,  but  it  is  by  no  means  impossible  that  solutions 
have  come  from  below.     The  veins  are  another  attendant  feature 
on  regional  metamorphism,  and  as  such  deserve  more  investiga- 
tion. 

1.06.23.  The  veins  that  contain  cassiterite  in  many  parts  of 
the  world,  and  that  yet  have  the  mineralogical   composition  of 
granite,  are  another  product  of  metamorphic  action,  both  contact 
and  regional.     The  gangue  minerals,  feldspar,  quartz,  and  mica, 
are  quite  characteristic  of  acid,  igneous  rocks,  but  the  coarseness 
of  the  crystallization  in  the  comparatively  narrow  veins  bars  out  a 
true  igneous  form  of  origin.     All  our  artificial  methods  of  repro- 
ducing these  minerals  lead  us  to  infer. that  the  veins  were  filled  at 
a  high  temperature  and  pressure,  therefore  at  considerable  depths, 
and  through  the  aid  of  steam.     Cassiterite  has  also  been  detected 
in  a  few  rare  cases,  under  such  circumstances  that  it  seemed  to  be 
an  original  mineral  in  igneous  granite.     It  is  probable,  therefore, 
that  it  may  be  an  original  and  early  crystallization  from  an  igne- 
ous magma,  much  as  is  magnetite.     More  observed  cases  would  be 
welcome  as  evidence. 

1.06.24.  The  great  iron  ore  bodies  of  Vermilion  Lake  have 
been  referred  by  N.  H.   and   H.  V.  Winchell,  in   the   American 


CLASSIFICATION  OF  ORE  DEPOSITS. 

-Geologist,  November,  1889,  p.  291,  to  a  precipitation  from  oceanic 
waters  in  the  vicinity  of  submarine  volcanic  eruptions  from  whose 
ejectamenta  they  derived  their  iron  and  silica.  The  hypothesis  is 
regarded  as  sufficient  to  account  as  well  for  the  siliceous  deposits 
associated  with  the  ore.  In  the  words  of  the  authors  :  "  Chemical 
precipitation  in  hot  oceanic  waters,  united  with  simultaneous  sedi- 
mentary distribution,  might  produce  the  Keewatin  ores  in  a  man- 
ner consistent  not  only  with  the  physical  conditions  that  prevailed 
at  the  time  of  their  formation,  and  with  the  structural  peculiari- 
ties which  they  exhibit,  but  also  in  accordance  with  the  known 
reactions  of  heated  alkaline  waters,  and  with  the  chemical  char- 
acter which  the  ores  are  known  to  possess."  This  hypothesis  in- 
troduces new  conditions  and  relations  which  are  necessarily  some- 
what speculative  ;  and  while  it  has  claims  to  attention,  it  may 
best  be  tested  by  the  general  consideration  of  the  geological  pub- 
lic before  being  placed  with  the  more  simple  and  certain  reactions 
grouped  in  the  scheme. 

1.06.25.  Fahlbands  should  be  mentioned  here.     The  term  re- 
fers to  belts  of  schists,  which  are  impregnated  with  sulphides,  but 
not  in  sufficient  amount  in  the  locality  where  the  name  was  first 
applied  (Kongsberg,  Norway)  to  be  available  for  ores.     The  de- 
composition of  the  sulphides  gave  the  schists  a  rusty  or  rotten  ap- 
pearance that  suggested   the   name.      Whether  the   ores  are  an 
introduction  into   the  schist,  subsequent  to  metamorphism,  or  a 
deposit  in  arid  with  the  original  sediment,  is  a  doubtful  point.     The 
practical  importance  of  these  fahlbands  lies  in  the  enriching  in- 
fluence that  they  exert  on  the  small  fissure  veins  that  cross  them. 

1.06.26.  The  phraseology  of  the  above  schemes  will  be  employed 
in  the  subsequent  descriptions.    In  addition,  much  emphasis  will  be 
placed  on  the    character  of  the   rocks  containing   the    deposits, 
whether  unaltered  sedimentary,   igneous,  or    metamorphic,    and 
whether  in  the  first  and  last  cases  igneous  rocks  are  near,  for  these 
considerations  enter  most  largely  into  questions  of  origin.     The 
ore  deposits  are  illustrated  by  examples,  somewhat  as  has  been 
done  by  the  best  of  modern  writers  abroad,  Von  Groddeck.    The 
word  "example  "  is  preferred  to  "type,"  which  was  employed  by 
Von  Groddeck,  because  it  implies  less  of  an  individual  character. 
"We  may  cite  deposits  under  different  metals  thus  which  all  might 
belong  to  one  type.     Under  each  metal  will  be  given,  first,  a  list 
of  general  treatises  and  papers.     These  will  be  marked  "Hist." 
when  especially   valuable  as  history,    and  "  Rec."  when    recom- 


<    . 


62  KEMP'S  ORE  DEPOSITS. 

mended  for  ordinary  examination.     If  not  marked  by  either,  they 
are  more  adapted  for  special  investigations. 

GENERAL  REFERENCES  ON  ORE  DEPOSITS. 

Ansted,  D.  T.  "  On  Some  Remarkable  Quartz  Veins,"  Quar.  Jour. 
Geol.  Sci.,  XIII.  246. 

Barns,  Carl.  "The  Electrical  Activity  of  Ore  Bodies,"  M.  E., 
XIII.  417.  (See  also  Becker's  Monograph  on  the  Comstock 
Lode,  p.  310,  for  references  to  other  papers.) 

Becker,  G.  F.  "The  Relations  of  the  Mineral  Belts  of  the  Pacific 
Slope  to  the  Great  Upheavals,"  Amer.  Jour.  Sci.,  III.  28, 
209.  1884. 

Belt,  Th.  Mineral  Veins:  an  Inquiry  into  their  Origin,  founded  on 
a  Study  of  the  Auriferous  Quartz  Veins  of  Australia.  Lon- 
don, 1861. 

Bischof,  G.  "  On  the  Origin  of  Quartz  and  Metalliferous  Veins," 
Jameson's  Journal,  April,  1845,  p.  344.  Abstract,  Amer. 
Jour.  Sci.,  I.  49,  396.  Advocates  aqueous  deposition. 

Brown,  A.  J.  "Formation  of  Fissures  and  the  Origin  of  their 
Mineral  Contents,"  M.  E.,  II.  215. 

Bulkley,  F.  G.  "  The  Separation  of  Strata  in  Folding,"  M.  E., 
XIII.  384. 

Campbell,  A.  C.  "  Ore  Deposits,"  Engineering  and  Mining  Jour- 
nal, July  17,  1880,  p.  39. 

Von  Cotta-Prime.  Ore  Deposits.  German,  1859;  English,  1870. 
Rec. 

Emmons,  E.  American  Geology,  134,  1853.  General  discus- 
sion. 

Emmons,  S.  F.     "  The  Structural  Relations  of  Ore  Deposits,"  M. 

E.,  XVI.  304.     Rec. 
"  Notes  on  Some  Colorado  Ore  Deposits,"  Proc.-   Colo.    Sci. 

Soc.,  II.,  Part  II.,  p.  35. 
"  On    the  Origin  of  Fissure  Veins,"  Proc.  Colo.  Sci.  Soc.,  II., 

p.  189.     Rec.     (See  also  R.  C.  Hills,  idem,  III.,  p.  177.) 
"The   Genesis  of  Certain  Ore  Deposits,"   M.  E.,  XV.    125. 
Rec. 

Endlich,  F.  M.  Hayderfs  Survey,  1873,  p.  276.  General  descrip- 
tion of  veins. 

Foster,  C.  L.  "  What  is  a  Mineral  Vein  ? "  Abstract  in  Geol. 
Mag.,  Vol.  L,  513. 


CLASSIFICATION  OF  ORE  DEPOSITS.  63 

Fox,  R.  W.  "Formation  of  Metallic  Veins  by  Galvanic  Agency," 
Amer.  Jour.  Set.,  I.  37,  199.  Abstract  from  London  and 
Edinburgh  Phil.  Mag.,  January,  1839. 

"  On  the  Electro-Magnetic  Properties  of  Metalliferous  Veins 
in  the  Mines  of  Cornwall,"  Amer.  Jour.  Sci.,  I.  20,  136. 
Abstract  of  paper  before  the  Royal  Society. 

Grimm,  J.     "Die  Lagerstiitten  der  Nutzbaren  Mineralien,"  1869. 

Von  Groddeck,  A.    "  The  Classification  of  Ore  Deposits,"  Engineer- 
ing and  Mining  Journal,  June  27,  1885,  p.  437. 
"  Die  Lehre  von  den  Lagerstiitten  der  Erze,"  1879.    Rec.    (See 
also  Engineering  and  Mining  Journalism.  3,  1880,  p.  2,, 
for  a  review  of  same.) 

Hague,  A.  D.     Mining  Industries,  Paris  Exposition,  1878. 

Henrich,  C.  "  On  Faults,"  Engineering  and  Mining  Journal, 
Aug.  24,  1889,  p.  158. 

Hunt,  T.  S.     "TheGeognostical  History  of  the  Metals,"   M.  E.,  I. 

331. 
"  The  Origin  of  Metalliferous  Deposits,"  in  "  Chemical  and 

Geological  Essays." 

"  Contributions  to  the  Chemistry  of  Natural  Waters,"  Amer. 
Jour.  Sci.,  II.  39,  176. 

Julien,  A.  A.  "On  the  Part  played  by  Humus  Acids  in  Ore 
Deposit,  Wall  Rock,  Gossan,"  etc.,  Proc.  A.  A.  A.  S.,  1879, 
pp.  382,  385. 

Keck,  R.      "  The    Genesis   of   Ore   Deposits,"    Engineering  and 

Mining  Journal,  Jan.  6,  1883,  p.  3. 

Review  of  Ore  Deposits  in  Various  Countries.  Denver,  1892. 
31  pages. 

Kemp,  J.  F.  "  A  Brief  Review  of  the  Literature  on  Ore  Deposits," 
School  of  Mines  Quarterly,  X.  54,  116,  326;  XI.  359;  XII. 
219. 

"  On  the  Filling  of  Mineral  Veins,"  School  of  Mines  Quar- 
terly, October,  1891. 

"  The  Classification  of  Ore  Deposits,"  School  of  Mines  Quar- 
terly, November,  1892. 

"  On  the  Precipitation  of  Metallic  Sulphides  by  Natural  Gas," 
Engineering  and  Mining  Journal,  December,  1890. 

Kleinschmidt,  J.  L.  "  Gedanken  ueber  Erzvorkommen,"  B.  and  IT. 
Zeit.,  1887,  p.  413. 

Koehler,  G.  "  Die  Storungen  der  Giinge,  Flotze,  u.  Lager."  Leip- 
zig, 1886.  Translated  by  W.  B.  Phillips  under  title  of  "Ir- 


64  KEMP'S   ORE  DEPOSITS. 

regularities  of  Lodes,  Veins,  and  Beds,"  Engineering  and 

Mining  Journal,  June  25,  1887,  p.  454;  also  July  2,  p.  4. 

Leconte,  J.     "  Mineral  Vein  Formation  in  Progress  at  Steamboat 

Springs  and  Sulphur  Bank,"  Amer.  Jour.  Sci.,  III.  25,  424. 

"Genesis   of  Metalliferous    Veins,"    Amer.   Jour.  Sci.,  July, 

1883.     See  other  references  under  "Mercury." 
Miller,  A.     Erzgange.     Basel,  1880. 

Necker.  "On  the  Sublimation  Theory,"  Proc.  Geol.  /Soc.  of  Lon- 
don, Vol.  I.,  p.  392;  also  Ansted's  Treatise  on  Geology, 
Vol.  II.,  p.  271.  Hist. 

Newberry,  J.  S.  "  The  Origin  and  Classification  of  Ore  Deposits," 
School  of  Mines  Quarterly,  I.,  1887,  1880.  Engineering  and 
Mining  Journal,  June  19  and  July  23,  1880.  A.  A.  A.  S., 
Vol.  XXXIL,  p.  243,  1883.  Rec. 

"The  Deposition  of  Ores,"   School  of  Mines  Quarterly,  V. 

329,  1884;  Engineering  and  Mining  Journal,  July  19,  1884. 

"  Genesis  of  Our  Iron  Ores,"  School  of  Mines  Quarterly,  II.  1, 

1880;  Engineering  and  Mining  Journal,  April    23,   1881. 

See  also  under  "  Iron." 

"  Genesis  and  Distribution  of  Gold,"  School  of  Mines  Quar- 
terly, III.,  1881;  Engineering  and  Mining  Journal,  Dec.  24 
and  31,  1881.     Rec. 
Ochsenius,  Carl.     "Metalliferous    Ore    Deposits,"    Geol.   Mag.,  I. 

310.    Hist. 
Pearce,  Rich.     "  On  Replacement  of  Walls,"   Chem.  News,  March 

3,  1865. 

Phillips,  J.  A.     "  The  Rocks  of  the  Mining  District  of   Cornwall 
and  Their  Relations  to  Metalliferous  Deposits,"  Quar.  Jour. 
Geol.  Soc.,  XXXI.  319. 
"A    Contribution   to  the  History  of   Mineral   Veins,"  Quar. 

Jour.  Geol.  Soc.,  XXXV.  390. 
"Treatise  on  Ore  Deposits,"  London,  1884. 
Pumpelly,  R.     Johnson's  Encycl,  Vol.  VI.,  p.  22.     Rec. 
Raymond,   R.   W.     "What  is  a  Pipe  Vein?"   Engineering  and 

Mining  Journal,  Nov.  23,  1878,  p.  361. 
Translation  of  Lottner,  and  general  remarks  on  classification. 

Min.  Stat.  West  of  Rocky  Mountains,  1870,  p.  447. 
Indicative  Plants,  M.  E.,  XV.  645. 
"  Geographical  Distribution  of  Mining  Districts  in  the  United 

States,"  M.  E.,  I.,  p.  33. 
Sandberger,  F.     "  Untersuchungen  iiber  Erzgange,"  1882;  "  Theo- 


CLASSIFICATION  OF  ORE  DEPOSITS.  65 

ries  of  the  Formation  of  Mineral  Veins,"  Engineering  and 
Mining  Journal,  March  15,  22,  29,  1884,  pp.  197,  212,  232. 

Wabner,  R.  "  Ueber  die  Eintheilung  der  Mineral  lagerstatten  nach 
ihrer  Gestalt,  sowie  die  Anwendung  und  die  Beniitzung  der 
Worte,  Lager  und  Flotz,"  B.  and  H.  Z.,  Jan.  2,  1891,  p.  1. 

Wadsworth,  M.  E.     "  The  Theories  of  Ore  Deposits,"  Proc.  Bos- 

ton  Soc.  Nat.  Hist.,  1884,  p.  197.     Rec. 

"  The  Lateral  Secretion  Theory  of  Ore  Deposits,"  Engineer- 
ing and  Mining  Journal,  May  17,  1884,  p.  364. 
"  Classification  of  Ore  Deposits,"  Hep.  of  Mich.  State  Geolo- 
gist, 1891-92,  p.  144.     Rec.     (See  Addenda.) 

Whitney,  J.  D.     "  Remarks  on  the  Changes  which  take  place  in 
the  Structure  and  Composition  of  Mineral  Veins  near  the 
Surface,"  Artier.  Jour.  ScL,  ii.  XX.  53. 
"  Metallic  Wealth  of  the  United  States,"  1854.     Rec. 

Whittlesey,  C.  "  On  the  Origin  of  Mineral  Veins,"  A.  A.  A.  S., 
XXV.  213. 

Williams,  Albert.  "Popular  Fallacies  Regarding  the  Precious 
Metal  Ore  Deposits,"  Fourth  Ann.  Hep  Director  U.  £, 
Geol.  Survey,  pp.  257-278. 


PAET  II. 

THE  ORE  DEPOSITS. 


CHAPTER  I. 

THE    IRON  SERIES    (IN    PART).— INTRODUCTORY    REMARKS   ON 
IRON  ORES.— LIMONITE.— SIDERITE. 

GENERAL  LITERATURE. 

Birkinbine,  J.     "  Prominent   Sources  of  Iron  Ore  Supply,"  M.  E., 

XVII.  715.     Statistical;  Rec. 

Various  statistical  papers  in  the  volumes  on  Mineral  Re- 
sources, U.  S.  Geol.  Survey,  especially  1886,  p.  39  ;  1887, 
p.  30. 

Chester,  A.  H.  "  On  the  Percentage  of  Iron  in  Certain  Ores/''  M.  E., 
IV.  219. 

Dunnington,  F.  P.  "  On  the  Formation  of  the  Deposits  of  Oxides 
of  Manganese,"  Amer.  Jour.  Sci.,  iii.,  XXXVI.  175.  The 
paper  treats  of  Iron  also. 

Hewitt,  A.  S. ,  "Iron  and  Labor,"  M.  E.,  September,  1889.     The 

paper  contains  valuable  statistics. 
"  A  Century  of  Metallurgy,"  M.  E.,  V.  164. 

Hunt,  T.  S.  "  The  Iron  Ores  of  the  United  States,"  M.  E.,  October, 
1890. 

Kimball,  J.  P.  "  Genesis  of  Iron  Ores  by  Isomorphous  and  Pseudo- 
morphous  Replacement  of  Limestone,"  Amer.  Jour.  Sci., 
September,  1891,  p.  231.  Continued  in  Amer.  Geologist, 
December,  1891. 

Julien,  A.  A.  "The  Genesis  of  the  Crystalline  Iron  Ores,"  Trans. 
Phil.  Acad.  Nat.  Sci.,  1882,  p.  335  ;  Engineering  and  Min- 
ing Journal,  Feb.  2,  1894. 

"  Origin  of  the  Crystalline  Iron  Ores,"  Trans.   JW.  Y.  Acad. 
Sci.,  II.,  p.  6  ;  Amer.  Jour.  Sci.,  iii.,  XXV.  476. 

Lesley,  J.  P.    "  The  Iron  Manufacturer's  Guide,"  1886.    Hist.  Rec. 

Newberry,  J.  S.  International  Review,  November  and  De- 
cember, 1874. 

"  Genesis  of  the  Ores  of  Iron,"  School  of  Mines  Quarterly, 
November,  1880.     Rec.     Amer.  Jour.  Sci.,  iii.,  XXI.  80. 


70 


KEMP'S   ORE  DEPOSITS. 


"  Genesis  of  the  Crystalline  Iron  Ores,"  Trans.  JV.   Y.  Acad. 

Sci.,  II.,  October,  1882.    Rec. 

Newton,  H.     "  The  Ores   of  Iron  :  Their  Distribution  with  Ref- 
erence to  Industrial  Centers,"  M.  E.,  III.  360. 
Pumpelly,  R.,  and  Others.    Tenth  Census,  Vol.  XV.,  1886,  especially 

pp.  3-17.     Rec. 
Reyer,  E.    "Geologic  des  Eisens,"  Oest.  Zeit.  f.  B.  und  IL,  1882, 

Vol.  XXX.,  pp.  89,  109. 
Rogers,  W.  B.     "  On  the  Origin  and  Accumulation  of   the  Proto- 

carbonate  of  Iron  in  the  Coal  Measures,"  Proc.  Bost.  Soc. 

Nat.  Hist.,  1856. 
Smock,  J.  C.     "On  the  Geological  Distribution  of  the  Ores  of 

Iron,"  M.  E.,  XII.  130. 
"  Iron  Mines  and  Iron  Ore  Districts  in  New  York,"  Bull.  N.  Y. 

/State  Mus.,  June,  188*9.     Rec. 
Swank,  J.  M.     Chapters  on  iron  in  Mineral  Resources,  U.  S.  Geol. 

Survey,  since  1883. 

"History  of  the  Manufacture  of  Iron  in  All  Ages."     1891. 
Whitney,  J.  D.     "Metallic  Wealth  of  the  United  States,"    1854, 

p.  425.    Hist. 
"  On  the  Occurrence  of  Iron  in  the  Azoic  System,"  A.  A.  A.  S., 

1855,  209  ;  Amer.  Jour.  Sci.,  ii.,  XXII.  38. 
Winchell,  N.  H.  and  H.  V.     "  The  Iron  Ores  of  Minnesota,"  Bull. 

N~o.  6,  Minn.  Geol.  Survey.    Part  IV.  contains  an  exhaustive 

review  of  methods  of  origin,   and  Part  V.  a  very  complete 

annotated  bibliography. 

Table  of  the  Iron  Ores,  Limonite,  Siderite,  Hematite,  Magnetite,  Pyrite. 


Fe. 

H2O. 

C02. 

S. 

Limonite  (brown  hematite,  bog  ore),  2Fe2O3 
3H2O  

59.89 

48.27 
70.0 
72.4 
46.7 

14.4 

37.92 

53.3 

Siderite  (Spathic  ore,  clay  ironstone,  black- 
band)  FeCO3  

Hematite  (red  and  specular),  FeoO«  .  .  •  .       . 

Magnetite  FeO  Fe2O3  or  Fe3O4  

Pyrite  FeS2  

2.01.01.  No  one  of  the  iron  ores  ever  occurs  pure  in  large 
amounts.  Only  a  few  closely  approach  this  condition.  The  largest 
quantity  of  rich  ore  as  yet  mined  in  the  United  States  was  doubt- 
less obtained  from  the  Lovers'  Pit  opening,  operated  by  Wither- 
bee,  Sherman  &  Co.,  on  Barton  Hill,  near  Mineville,  N.  Y.  The 


THE  IRON  SERIES  (IN  PART).  71 

record  shows  that  40,000  tons  of  magnetite  averaged  68.6^ 
Fe.  In  general  the  ores  run  much  less.  The  richest  are  the 
magnetites  and  specular  hematites.  In  numerous  instances  the 
mines  of  the  Lake  Champlain  district  have  produced  the  former, 
and  Lake  Superior  mines  the  latter,  at  63  to  65$,  or  even  more. 
The  separated  ores  in  the  Lake  Champlain  district  run  about  65$. 
The  unseparated  ores  have  much  less,  and  indeed  all  percentages  from 
50  to  65.  Thus  the  lump  ore  (shipped  as  mined)  from  Chateaugay, 
N.  Y.,  has  about  50$.  The  Cornwall  (Penn.)  magnetite  holds  even 
less.  The  Clinton  red  hematites  from  New  York  afford  about  44$  in 
the  furnace,  as  the  result  of  long  experience.  The  limonites,  as  usu- 
ally mined,  produce  from  40  to  50$.  The  crude  spathic  ores  are  the 
lowest  of  all,  and  in  the  variety  black-band  may  even  be  about  30$. 
They  are  easily  calcined,  however,  and  on  losing  their  carbonic 
acid,  moisture,  and  bituminous  matter  the  percentage  of  iron  rises 
a  third  or  more'.  A.  H.  Chester  found  in  1875,  as  the  result  of  an 
endeavor  to  determine  the  average  yield  of  certain  standard  ores  in 
the  furnace,  Lake  Superior  specular,  62.5$  ;  Lake  Superior  limonite, 
49.5#  ;  Rossie  (K  Y.)  red  hematite,  54.5$;  Wayne  County  (N.  Y.) 
Clinton  ore,  40l 

2.01.02.  The  common  impurities  in  iron  ores  are  the  common 
elements  or  oxides  that  enter  most  largely  into  rocks,  and  those 
which  make  up  the  walls  of  the  deposit  are  usually  the  ones  that 
appear  most  abundantly  in  the  ore.  Silica  (SiO2),  alumina  (A12O3), 
lime  (CaO),  magnesia  (MgO),  titanium  oxide  (TiO2),  carbonic  acid 
(CO2),  and  water  (H2O)  appear  in  large  amounts  and  determine  to 
a  great  extent  the  character,  fluxing  properties,  etc.,  of  the  ore- 
With  these,  and  of  more  far-reaching  influence,  are  smaller  amounts 
of  sulphur  and  phosphorus.  The  last  two  and  titanium  chiefly  de- 
termine the  character  of  the  iron  which  is  yielded  in  the  furnace 
and  are  the  first  foreign  ingredients  sought.  The  sulphur  is  present 
in  pyrite,  the  phosphorus  in  apatite.  As  is  well  known,  0.1$  of 
phosphorus  is  set  as  the  extreme  limit  for  Bessemer  pig  irons,  and 
as  ores  for  these  command  the  best  market,  they  are  eagerly 
sought.  To  obtain  the  allowable  limit  of  phosphorus  in  the  ore,  its 
percentage  in  iron  is  divided  by  1000.  Thus  a  65.3$  ore  should 
not  have  over  0.065$  phosphorus  to  be  ranked  as  Bessemer.  If  at 
the  same  time,  with  sufficiently  low  phosphorus,  the  gangue  is 
highly  siliceous,  a  composition  desirable  for  Bessemer  practice, 
ores  may  be  of  value,  although  of  comparatively  low  grade  and  re- 
motely situated. 


72  KEMP'S   ORE  DEPOSITS. 

Thus  the  lump  magnetite  of  the  Chateaugay  mines,  in  the 
northern  Adirondacks,  affords  but  50$  iron,  yet  it  is  mined  and 
shipped  forty  miles  to  Plattsburg,  and  thence  four  hundred  miles  to 
the  furnaces.  It  has  18.44  SiO2  and  only  0.029  P  and  0.052  S.  Late 
operations  in  the  siliceous  specular  hematites  of  Pilot  Knob,  Mo., 
have  utilized  low-grade  ore  rejected  in  former  years.  Other  in- 
stances could  be  cited.  On  the  other  hand,  a  moderate  amount  of 
phosphorus  is  not  only  no  drawback  for  ordinary  foundry  irons 
and  such  as  are  to  be  subjected  to  tool  treatment,  but  it  is  a  prime 
necessity.  Excessive  amounts  are  desired  only  for  weak  but  very 
fluid  irons.  Considerations  like  these,  which  are  rather  metallur- 
gical than  geological,  largely  determine  the  availabilty  of  a  deposit, 
and  to  some  extent  the  present  locations  of  the  mining  districts. 

2.01.03.  Iron  itself  is  one  of  the  most  abundant  and  widely  dis- 
seminated elements  entering  into  the  composition  of  the  earth.     A 
careful  estimate  of  the  probable  average  composition  of  the  outer 
crust  of  the  earth  afforded  Alexander  Winch  ell  (Geological  Studies, 
pp.  19,  20)  the  results  in  Column  I.    Prestwich,  the  English  geologist, 
gives  the  figures  in  Column  II.     (Geology,  Vol.  I.,  p.  10.) 

I.  II. 

0 45  0 50 

Si 25  Si 25 

Al 10  Al 10 

Fe 8  Ca 4.5- 

Ca 6  Mg , 3.5 

Na 2.5  Na 2 

C,  H,  S,  N,  C»,  Mg,  etc..  •  1.5  C,  Fe,  S,  Cl 2.4 

K 2  K 1.6 

100.  99.0 

The  figures  were  obtained  by  taking  the  general  prevalence  of 
the  common  rocks  and  estimating  on  their  known  compositions. 
In  WinchelPs  estimate  iron  is  fourth  in  abundance,  while  in  Prest- 
wich's  it  is  ninth.  Either  case  illustrates  its  great  abundance  and 
wide  distribution,  although  the  former  with  much  greater  em- 
phasis. 

2.01.04.  A  general  comparison  of  the  tabulated  analyses  of  ig- 
neous rocks  (See  Roth's  Gesteinsanalysen  and  Allgemeine  Chem. 
und  PhysikaL   Geologie)   ^hows  that  the  granites  contain  0.0-7$ 
iron  oxides,  the  porphyries  0.0-1 4#,  the  rhyolites  0.0-8$,  the  di- 
orites  and  diabases  4-16$,  the  andesites  3-15$,  the  basalts  12-20$. 


THE  IRON  SERIES  (IN  PART).  r/3 

Limestones  invariably  have  at  least  small  amounts,  and  at  times 
very  considerable  percentages.  Sandstones  are  often  low,  but  not 
seldom  are  stained  through  and  through.  The  metamorphic  rocks 
offer  close  analogies  to  the  igneous.  In  general  distribution  and  in 
quantity,  iron  leads  the  list  of  the  distinctively  metallic  elements. 
Its  peculiar  property  of  possessing  two  oxides,  of  different  chemical 
quantivalence,  assists  greatly  in  the  formation  of  ores  and  the 
general  circulation  of  the  metal.  This  is  set  forth  under  the 
following  examples. 

LIMONITE. 

2.01.05.  Example  1.    Bog  Ore. — Beds  of  limonite,  superficially 
formed  in  marshes,  swamps,  and  pools,  of  standing  water.     The 
general  circulation    of  water  through  the  rocks   enables  it  very 
frequently  to  take  up  iron  in  solution.     Ferruginous  i&inerals  are 
among  the  first  and  easiest  that  fall  a  prey  to  alteration.     Car- 
bonic acid  in  the  water  aids  in  dissolving  the  iron,  which  thus,  in 
waters  containing  an    excess  of  CO2,  passes  into  solution  as  the 
protocarbonate  FeCO3.    Organic  acids  may  also  play  a  part.     The 
alteration  of  pyrite  affords  sulphuric  acid  and  ferrous  sulphate, 
and  the  latter  enters  readily  into  solution.     On  meeting  calcium 
carbonate,  both  ferric  and  ferrous  sulphate  are  decomposed,  yield- 
ing in  the  first  case  calcium  sulphate,  ferric  hydrate,  and  carbonic 
acid;  in  the  second,  if  air  is  absent,  ferrous  carbonate  and  calcium 
sulphate,  but   on   the  admission  of  air  ferric  hydrate  soon  forms. 
(See  F.  P.  Dunnington,  Amer.  Jour.  Sci.,  iii.,  XXXVI.  176.     Ex- 
periments 10  and  11.     See  also  Addenda.) 

2.01.06.  Bodies  of  limonite  that  become  exposed  to  a  reduc- 
ing action  from  the  favorable  presence  of  decaying  organic  mat- 
ter likewise  furnish  the  protocarbonate.     In    general  it  may  be 
stated  that  free  oxygen  must  be  absent  or  only  in  small  quantity 
where  solution  takes  place.     Sooner  or  later  the  ferruginous  (or 
chalybeate)  waters  come  to  rest,  especially  in  swamps.    The  proto- 
salt  is  exposed  to  the  evaporation  of  the  excess  of  CO2,  that  held 
it  in  solution,  and  also  to  the  action  of  oxygen.     Two  molecules 
of  carbonate,  together  with  one  atom  of  oxygen  and  some  water, 
break  up  into  CO2  and  Fe2O3,  x  H2O.     The  latter  forms  as  a  scum 
and  then  sinks  to  the  bottom  and  accumulates  in  cellular  masses. 
The  sesquioxide  is  insoluble,  and  as  against  ordinary  waters  free 
from  reducing  agents  it   remains  intact.     Deposits  of  mud  and 
peat  forming  above  may  cover  the  beds  with  a  protecting  layer. 


74  KEMP'S   ORE  DEPOSITS. 

Hardly  a  bog  exists  which  does  not  show,  when  cut  in  cross  sec- 
tion, the  bog  ore  beneath.  Frequent  associates  of  the  ore  are 
diatomaceous  earth  and  shell  marl,  formed  by  the  remains  of  or- 
ganisms which  once  inhabited  the  waters.  At  times  excellent  im- 
pressions of  leaves  and  shells  are  preserved  in  the  ore.  Such  ore 
bodies  are  not  often  practically  available  on  account  of  the  low 
percentage  in  iron,  due  to  the  abundance  of  sand  and  silt  washed 
in,  and  to  the  frequent  large  amounts  of  sulphur1  and  phosphorus 
which  they  contain.  The  sulphur  is  present  in  pyri.te  and  the 
phosphorus  in  vivianite,  sometimes  in  sufficient  quantity  to  be 
visible  (Mullica  Hill,  N.  J.,  var.  Mullicite).  In  certain  parts  of 
the  country  bog  deposits  have  been  and  others  may  yet  be  utilized. 

2.01.07.  In  eastern  North  Carolina  bog-ore  beds  are  frequent 
and  are  found  lying  just  below  the  grass  roots.    Scattered  nodules 
occur  in  the  overlying  soil,  which  are  succeeded  by  a  bed  three 
feet  or  less  in  thickness,  resting  on  sand.1 

In  Hall's  Valley  and  Handcart  Gulch,  Park  County,  Colorado,  in- 
teresting and  extensive  deposits  of  limonite  are  in  active  process  of 
formation.  The  iron  comes  from  neighboring  great  beds  of  pyrite.2 

Bog  ore  of  good  quality  has  recently  been  reported  from  the 
vicinity  of  Great  Falls,  Mont.3 

At  Port  Townsend  Bay,  in  the  vicinity  of  Puget  Sound,  and  at 
the  Patton  mines,  near  Portland,  Ore.,  the  ores  are  of  such  quality 
as  to  be  available.4  (For  bog  ore  in  Quebec,  see  Addenda.) 

2.01.08.  A  somewhat  different  variety  of  Type  1  is  formed  when 
the  ferruginous  waters  come  to  rest  in  the  superficial  hollows  of 
the  rock  which  has  furnished  the  iron.     Depressions  in  the  serpen- 
tines of  Staten  Island,  N.  Y.,  carry  such  deposits,  and  the  iron  is 
referred  by  N.  L.  Britton  to  the  leaching  of  the  underlying  rock. 
The   ore   contains  a  notable  percentage  of  chromium,  which  is 
known  to  occur  in  the  serpentine.    The  mines  have  been  in  former 
years  quite  large  producers.     Similar  limonites  occur  at  Rye,  N.  Y.5 

1  W.  C.  Kerr,  Geology  of  North  Carolina,  1875,  p.  218.    B.  Willis, 
Tenth  Census,  Vol.  XV.,  p.  302. 

2  R.   Chauvenet,   "The  Iron  Resources  of  Colorado,"  M.  E.,  June, 
1889.     "  Notes  on  Iron  Prospects  in  Northern  Colorado,"  Ann.  Eep.  Colo. 
School  of  Mines,  1886. 

3  Mineral  Resources,  U.  S.  Oeol.  Survey,  1888,  p.  34. 

4  B.  T.  Putnam.  Tenth  Census,  Vol.  XV,  p.  496. 

8  N.  L.  Britton,  School  of  Mines  Quarterly,  May,  1881.  Compare  also 
Amer.  Jour.  Sci.y  iii.,  XX.  32,  and  XXII.  488. 


THE  IRON  SERIES  (IN  PART).  75 

At  the  Prosser  mines,  near  Portland,  Ore.,  deposits  of  limonite 
are  found  in  the  superficial  hollows  of  a  Tertiary  basalt  of  the 
Cascade  range.  The  ore  contains  roots  and  trunks  of  trees,  and  is 
covered  by  a  later  flow  of  basalt.  Similar  bodies  of  limonite  re- 
sulting from  basalt  are  known  in  the  German  province  of  Hesse 
and  in  Ireland.1 

2.01.09.  The  limonite  sand,  or  oolite,  that  forms  in  the  Swedish 
lakes   about  ten  meters  from  the  banks  and  in  water  up  to  ten 
meters  in  depth  is  another  variety  of  this  type.     A  layer  half  a 
meter   and  less  in  thickness  accumulates  every  fifteen  to  thirty 
years  and  is  periodically  dredged  out.     The  ore  precipitates  first 
as  a  slime  that  breaks  up   afterward  into  small   concretions.     It 
has  been  thought  that  the  formation  of  these  and  similar  bodies  of 
limonite  has  been  aided  by  small  algae  and  other  plants  or  micro- 
scopic organisms.2 

2.01.10.  Example  2.      Bodies  of  limonite  in  cavities  of  fer- 
ruginous rocks,  on  the  outcrop,  or  below  the  surface,  which  have 
resulted  either  from  the  alteration  of  the  rock  in  situ  or  from  its 
partial  replacement  by  limonite.     Residual  clay,  quartz,  and  other 
remains  of  alteration   usually   occur  with  the  ore.     Ferruginous 
limestones  are  the  commonest  sources  of  such  deposits,  but  other 
rocks  may  afford  them.     The  deposits  are  not  limited  to  any  one 
geological  series,  but  in  different  parts  of  the  country  occur  when- 
ever the  conditions  have  been  favorable.     Some  of  the  ore  may 
have  been  brought   in  by  subterranean  circulations  which   have 
leached  the  neighboring  rocks.     Considerable  limonite  has  also  re- 
sulted from  the  weathering  of  clay  ironstone  nodules  and  black- 
band  beds  in  the  Carboniferous  system  (to  be  mentioned  later),  and 
not  infrequently  from  the  alteration  of  nodular  masses  of  pyrites. 

1  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  16,  on  the  Oregon  ore. 
Tasche,  Berg.-  und  Hutt.  Zeit.,  1886,  p.  209;  also  Wurtemberger,  Neues 
Jahrb.,  1867,  p.  685,  on  the  Hessian  ores.    Tate  and  Holden,  "On  the  Iron 
Ore  Associated  with  the  Basalt  of  Northeastern  Ireland,"  Quar.  Jour. 
Geol  Sci  ,  XXVI.  151. 

2  F.  M.  Stapff,  Zeitschr.  d.  d.  geolog.  Gesellsch.,  1866,  Vol.  XVIII.,  p.  8, 
on  the  geology  of  the  ores.  Sjogrun,  Berg.-  und  Huett.  Zeit.,  1865,  p.  116, 
on  the  agency  of  algas.  On  the  general  formation  of  bog  ores  the  fol- 
lowing papers  are  of  interest:  G.  J.  Brush  and  C.  S.  Rodman,  "Ob- 
servation on  the  Native  Hydrates  of  Iron,"  Amer.  Jour.  Sci.,  ii.,  XLIV. 
219;  J.  S.  Newberry,  School  of  Mines  Quarterly,  November,  1880;  J.  Roth, 

Chem.  und  Phys.  Geologie,  I.,  pp.  58,  97,  221 ;  F.  Senft,  Humus,  Marsch> 

Tor/-  und  Limonit-bildungen. 


70 


KEMP'S    ORE  DEPOSITS. 


The  limonite  is  in  cellular  lumps,  in  pipes,  pots,  and  various  imita- 
tive forms  which  often  have  a  beautiful  luster.  The  hollow  masses 
have  in  general  resulted  form  the  filling  of  reticulated  cracks  in 
shattered  rock.  The  ore  thus  deposits  around  the  cores  of  country 
rock,  which  afterward  are  removed,  leaving  a  hollow  shell  or  geode. 
(See  Tenth  Census,  Vol.  XV.,  pp.  275,  369,  370.) 

2.01.11.  Reserving  the  Siluro-Cambrian  limonites  for  a  subtype 
the  ore  bodies  are  described  in  order  from  east  to  west,  taking  up 
first  the  Alleghany  region,  then  the  Mississippi  Valley,  and  lastly 


FIG.   8. — Section  of  the  Hurst  limonite  bank,   Wythe  County,   Virginia, 

illustrating  the  replacement  of  shattered  limestone  with  limonite 

and  the  formation  of  geodes  of  ore.    After  E,  R,  Benton, 

Tenth  Census,  Vol.  XV.,  p.  275. 


the  Rocky  Mountains.  The  limonites  of  New  England  and  New 
York  belong  in  the  subsequent  subtype,  as  do  those  of  eastern 
Pennsylvania  and  the  more  important  ones  in  Virginia,  Tennessee, 
Georgia,  and  Alabama.  In  central  and  western  Pennsylvania, 
however,  not  a  small  amount  is  obtained  from  the  higher  lying 
terranes.  The  Hudson  River  slates  furnish  small  amounts  in 
Franklin  County,  which  are  thought  by  McCreath  to  have  resulted 
from  the  alteration  of  nodules  of  pyrites.  (Second  Penn.  Geol.  Sur- 
vey, MS,  p.  x.)  The  Medina  sandstones  contain  highly  ferrugi- 
nous portions  in  Huntingdon  County.  (McCreath,  Second  Penn. 
l.  Survey,  MM,  p.  198.)  The  Lower  Helderburg  and  Oriskany 


THE  IRON  SERIES  (IN  PART).  77 

are  locally  quite  productive  in  Blair  County,  affording  several  great 
banks  of  ore.  (Report  MM,  196,  M3,  p.  33.)  The  Oriskany  is  of 
greater  importance  in  Virginia  than  in  Pennsylvania.  East  of 
these  last  mentioned  exposures,  and  in  southern  Carbon  County,  is 
a  bed  of  paint  ore  between  the  Oriskany  and  the  Marcellus.  (C. 
E.  Hesse,  "  The  Paint-Ore  Mines  at  Lehigh  Gap,"  M.  K,  New  York 
meeting,  1890.)  The  Marcellus  is  the  most  productive  of  the  Devo- 
nian stages.  It  affords  considerable  ore  in  Perry  County  (Report 
MM,  p.  193  ;  M3,  p.  29),  Juniata  County,  Mifnin  County,  Hunting- 
don County  (Report  M,  p.  66  ;  MM,  p.  194  ;  M3,  p.  140),  Fulton 
County  (Report  M3,  p.  42),  and  Franklin  County  (Report  M3, 
p.  1).  All  these  are  in  southern  Pennsylvania.  Lesley  states 
(Iron  Manufacturers'  Guide,  p.  650)  that  the  ore  is  weathered  car- 
bonate. As  shown  under  Example  4,  beds  of  carbonate  ore  occur  in 
Ulster  County,  New  York,  in  the  Marcellus.  (Additional  details 
on  the  above  Pennsylvania  deposits  will  be  found  in  the  geological 
reports  on  the  particular  counties.) 

2.01.12.  As  already  remarked,  the  greater  part  of  the  limonites 
in  Virginia  belong  under  the  Siluro-Cambrian  division  and  are  there 
described,  but  in  the  James  River  basin,  on  Purgatory  and  May's 
Mountains,  there  are  deposits  in  sandstones  of  the  Clinton.  (J.  L. 
Campbell,  The  Virginias,  July,  1880.)  Other  limonite  beds  occur 
in  the  Oriskany  on  Brushy  Mountain  (Longdale  mines),  on  Rich 
Patch  Mountain  (Low  Moor  mines,  involving  also  the  Medina),  on 
Warm  Spring  Mountain,  and  on  Peter  Mountain.  In  the  Shenan- 
doah  Valley,  on  Massanutton  Mountain,  the  limonite  is  referred  by 
Prime  to  the  Clinton  stage.  (The  Virginias,  March,  1880,  p.  35.) 
On  North  Mountain  it  lies  in  the  Oriskany,  according  to  Camp- 
bell (The  Virginias,  January,  - 1880,  p.  6),  and  on  the  Great 
North  Mountain  in  the  Upper  Silurian.  Considerable  oxide  of 
zinc  collects  in  the  tunnel  heads  of  the  furnaces  running  on  Low 
Moor  ores,  indicating  the  presence  of  this  metal  in  the  limonite.1 

The  iron  ores  in  Kentucky  are  found  in  three  widely  separated 
districts,  one  near  Greenup,  in  the  northeastern  corner  of  the  State, 
known  as  the  Hanging  Rock  region  ;  the  second  near  the  central 
part  along  the  Red  and  Kentucky  rivers,  known  as  the  Kentucky 
and  Red  River  region  ;  and  the  third  in  the  southwestern  part  near 

1  E.  C.  Means,  "Flue  Dust  at  Low  Moor,  Va.,"  M.  E.,  1888;  E.  C. 
Pechin,  "  Virginia  Oriskany  Iron  Ores,"  Engineering  and  Mining  Jour- 
nal, Aug.  13,  1892,  p.  150. 


78      •  KEMPS  ORE  DEPOSITS. 

Lyon  and  Trigg  Counties,  known  as  the  Cumberland  River  region. 
Although  the  first  two  contain  much  limonite,  it  has  altered  from 
nodules  of  carbonate,  and  the  ores  are  therefore  described  under 
Example  5.  One  locality  near  Owingsville,  in  the  second  region, 
has  limonites  altered  from  the  Clinton  hematite.  (See  Example 
6.)  The  Cumberland  region  affords  limonites  in  the  Subcarbonif- 
erous.  They  are  in  rounded  masses,  either  solid  or  hollow,  and 
are  distributed  through  a  red  clay  along  with  angular  fragments  of 
chert.  The  limonite  pots  are  themselves  filled  with  clay  or  water.1 

2.01.13.  In  Tennessee  the  limonites  of  the  eastern  portion  come 
mostly  under  Example  2a.     In  the  west  they  are  a  southern  ex- 
tension of  the  pot-ore  deposits  of  Kentucky,  and  show  the  same  as- 
sociated chert  and  clay.     Safford  has  called  the  rocks  containing 
them  the  Siliceous  Group.     The  west  Tennessee  district  projects 
into  Alabama  to  a  small  extent.2 

2.01.14.  The  principal  limonite  deposits  of  Alabama  come  under 
Example  2a,  as  do  those  of  western  North  Carolina  and  Georgia. 
Some  limonite  is  produced  in  Ohio,  but  it  is  all  weathered  carbon- 
ate  and   is   mentioned   under   Example   5.      Limonites   form   an 
abundant  ore  in  the  Marquette  district  of  Michigan,  but  are  men- 
tioned with  the  vastly  greater  deposits  of  hematite  under  Example 
9a.     Deposits  of  brown  hematite  are  worked  in  a  small  way  in  the 
southeastern    part  of  Missouri,  where   they  rest  upon  Cambrian 
strata   and  have  a  marked  stalactitic  character.     (P.  N.  Moore, 
Geol  Survey  of  Missouri,  Report  for  1874;   F.  L.   Nason,  Mo. 
Geol.  Survey,  1 892,  II.,  p.  158.)    Limonites  referred  to  the  Cretaceous 
by  N.  H.  Winchell  occur  in  western  Minnesota.     (Bull.  VL,  Minn. 
Geol.  Survey,  p.  151.)     (For  Arkansas  limonite,  see  Addenda.) 

2.01.15.  In  eastern  Texas,  along  the  latitude  of  the  northern 
boundary  of  Louisiana,  extended  beds  of  limonite  are  found  cap- 
ping the  mesas  or  near  their  tops,  and  associated  with  glauconitic 
sands  oi  Tertiary  age.      They  are  described   by  Penrose   (First 
Ann.  Rep.  Texas  Geol.  Survey,  p.  66  ;  also  G.   S.  A.,  III.  44)  as 
(1)  Brown  laminated  ores,  (2)  Nodular  or  geode  ores,  (3)  Conglom- 
erate ores.      The  first  form    extended  beds   whose   firmness  has 
prevented  the  erosion  of  the  hills,  and  which  are  thought  to  have 
originated  by  the  weathering  of  the  pyrites  in  the  greensands  and 

1  W.  B.  Caldwell,  "  Report  on  the  Limonite  Ores  of  Trigg,  Lyon,  and 
Caldwell  Counties,"  Kentucky  Geol.  Survey,  New  Series,  Vol.  V.,  p.  251. 

2  W.  M.  Chauvenet,  Tenth  Census,  Vol.  XV.,  p.  357 ;  T.  H.  Safford, 
Geology  of  Tennessee,  p.  350. 


THE  IRON  SERIES  (IN  PART).  79 

from  the  iron  of  the  glauconite  itself.  The  second  group  occur 
just  north  of  the  last,  and  have  probably  resulted  from  the  altera- 
tion of  clay  ironstone  nodules  (Cf .  Example  5),  while  the  third  has 
formed  in  the  streams  by  the  erosion  of  the  first  two  and  from  the 
smaller  ore-streaks  and  segregations.  Limonite  also  occurs  in 
northwestern  Louisiana.  (Mineral  Resources,  1887,  p.  51.)  Limon- 
ite is  known  in  a  number  of  localities  of  Colorado.  The  chief  pro- 
ductive mines  lie  in  Saguache  County,  near  Hot  Springs.  They 
furnish  a  most  excellent  ore  from  cavities  in  limestones,  which  are 
generally,  but  with  no  great  certainty,  considered  Lower  Silurian. 
R.  Chauvenet  states  that  the  ores  yield  about  43$  Fe  in  the 
furnace.1 

A  great  body  of  limonite  nodules,  bedded  in  red,  residual  clayr 
has  been  reported  from  the  Clinton  series  of  Allamakee  County, 
Iowa.  (E.  Orr,  Amer.  Geologist,  Vol.  L,  p.  129.) 

Much  limonite  occurs  at  Leadville  in  connection  with  the  lead- 
silver  ores,  and  is  used  as  a  flux  by  the  lead  smelters.  Some  grades 
low  in  silver  and  rich  in  manganese  have  even  been  used  for  spiegel 
at  Pueblo.  For  the  geological  relations,  see  Example  30. 

2.01.16.  Limonites  in  supposed  Carboniferous  limestone  occur 
in  the  East  Tintec  mining  district  in  Utah,  and  seem  to  be  as- 
sociated with  a  decomposed  eruptive  rock,  somewhat  as  at  Lead- 
ville.   The  limonite  is  chiefly  used  as  a  flux  by  lead-silver  smelters.2 

2.01.17.  Example  2a.     Siluro- Cambrian  Limonites. — Beds  of 
limonite  in   so-called  hydromica  (talcose,   damourite),   slates  and 
schists,  often  also  with  limestones  of  the  Cambrian   and  Lower 
Silurian  systems  of  the  Appalachians.     The  great  extent,  the  geo- 
logical relations,  and  the  importance  of  these  deposits  warrant  their 
grouping  in  a  subtype  by  themselves.     They  extend  along  the  Ap- 
palachians   from  Vermont  to  Alabama,   and    are   in  the  "  Great 
Valley,"  as  it  was  early  termed,  which  marks  the  trough  between 
the  Archaean  on  the  east  and  the  first  corrugations  of  the  Paleozoic 
rocks,  often  metamorphosed,  on  the  west.     The  masses  of  limonite 
are  buried  in  ocherous  clay,  and  the  whole  often  preserves  the  gen- 
eral structure  of  the  schistose  rocks  which  they  have  replaced.     The 

1  R.  Chauvenet,  ' '  Preliminary  Notes  on  the  Iron  Resources  of  Col- 
orado," Ann.  Rep.  Colo.  State  School  of  Mines,   1885,  p.  21 ;  "Iron  Re- 
sources of  Colorado,"  M.  E.,  1889.   F.  M/Endlich,  Hayderis  Reports,  1873,. 
p.  333.     B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  482.     C.  M.  Rolker, 
"  Notes  on  Certain  Iron  Ore  Deposits  in  Colorado,"  M.  E.,  XIV.  266,   Rec. 

2  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  490.  • 


80  KEMP'S   ORE  DEPOSITS. 

original  stringers  of  quartz  remain  following  the  original  folds. 
Dolomitic  limestone  often  forms  one  of  the  walls,  and  still  less 
often  (but  especially  in  New  England)  masses  of  siderice  are  found 
inclosed.  Manganese  is  at  times  present,  and  in  Vermont  is  of  some 
importance  of  itself. 

2.01.18.  The  deposits  begin  in  Vermont,  where  in  the  vicinity 
of  Brandon  they  have  long  been  ground  for  paint.  A  curious  pocket 
of  lignite  occurs  with  them  and  affords  Tertiary  fossils.  This 
prompted  President  Edward  Hitchcock,  about  1850,  to  refer  all  the 
limonites  to  the  Tertiary,  making  an  instructive  example  of  the  oc- 
casional hasty  generalizations  of  the  early  days.  Lignite  has  also 
been  found  at  Mont  Alto,  Penn.  In  northeastern  Massachusetts, 
at  Richmond  and  West  Stockbridge  ;  and  just  across  the  State  line, 
in  Columbia  and  Dutchess  counties,  New  York,  and  at  Salisbury, 
Conn.,  the  mines  are  large,  and  were  among  the  first  worked  in  the 


Slate 

.Probably  Limes.tpoe 

FIG.  9. — Geological  section  of  the  Amenia  Mine,  Dutchess  County,  New 

York,  illustrating  a  Siluro-Cambrian  limonite  deposit.    After 

B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  133. 

United  States.  The  limonite  forms  geodes,  or  "pots,"  pipes, 
stalactitic  masses,  cellular  aggregates,  and  smaller  lumps  from 
which  the  barren  clays  and  ochers  are  removed  by  washing.  The 
ore  is  but  a  fraction  of  the  material  mined  and  occurs  in  irregular 
streaks  through  the  clays,  etc.  It  is  mostly  obtained  by  stripping 
and  open  cuts,  and  only  rarely  by  underground  mining,  which 
would  present  difficulties  with  such  poor  material  for  walls.1 

1  J.  D.  Dana,  "  Occurrence  and  Origin  of  the  New  York  and  New  Eng- 
land Limonites,"  Amer.  Jour.  Sci.,  iii.,  XIV.  132,  and  XXVIII.  398.  Rec. 
E.Hitchcock,  "Description  of  a  Brown  Coal  Deposit  at  Brandon,  Vt., 
with  an  Attempt  to  determine  the  Geological  Age  of  the  Principal  Ore 
Beds  of  the  United  States,"  Amer.  Jour.  Sci.,  ii.,  XV.  95 ;  Hist.  Geol. 
Survey  of  Vermont,  I.  233.  See  also  Lesley,  below.  A.  L.  Holley,  "  Notes 
on  the  Salisbury  (Conn.)  Iron  Mines  and  Works,"  M.  E.,  VI.  220.  J.  P. 
Lesley,  "Mont  Alto  (Penn.)  Lignites,"  Proc.  Amer.  Acad.  Sci.,  1864,  463- 
482 ;  Amer.  Jour.  Sci.,  ii.,  XL.  119.  L.  Lesquereux,  "  On  the  Fossil  Fruits 
found  in  Connection  with  the  Lignite  at  Brandon,  Vt.,"  Amer.  Jour.  Sci., 


THE  IRON  SERIES  (IN  PART).  81 

A  gap  occurs  in  the  succession  of  the  deposits  across  southern 
New  York  and  New  Jersey,  although  a  few  minor  ones  are  known 
in  the  western  part  of  the  latter  State,  in  the  magnesian  limestone 
of  the  valleys  between  the  hills  of  gneiss.1 

2.01.19.  In  Lehigh  County  and  to  the  southwest  through  York 
County,  in  eastern  Pennsylvania,  the  limonites  are  again  developed 
in  great  amount,  and  run  southwesterly,  with  few  gaps,  to  Alabama. 
It  is  in  this  portion  that  the  "  Great  Valley "  (called  also  the 
Cumberland  Valley,  or  Valley  of  Virginia)  is  especially  marked. 
Wherever  the  great  limestone  formation,  No.  II.  of  Rogers,  is 
developed  the  ores  are  found.  This  corresponds  to  the  Calciferous, 
Chazy,  and  Trenton  of  New  York.  Limonites  also  occur  still 
lower  in  the  Cambrian  at  about  the  horizon  of  the  Potsdam  sand- 
stone or  in  the  overlying  slates.  According  to  McCreath,  they  are 
distinguishable  in  Pennsylvania  as  ores  at  the  top,  ores  in  the 
middle,  and  ores  at  the  bottom  of  the  great  limestone  No.  II. 
Those  at  the  top  form  the  belt  along  the  central  part  of  the  valley 
where  the  Trenton  limestone  underlies  the  Utica  or  Hudson  River 
slates.  Those  in  the  middle  are  connected  with  various  horizons 
of  ferruginous  limestones  in  the  Chazy  and  Calciferous.  Those  at 
the  bottom  along  the  north  or  west  part  of  the  South  Mountain- 
Blue  Ridge  range  are  geologically  connected  with  the  Potsdam 
sandstone,  or  the  slates  which  intervene  between  it  and  the  base  of 
the  Calciferous.  (Second  Penn.  Survey,  Rep.  MM,  p.  199.)  Cobalt 
has  been  detected  on  those  of  Chester  Ridge  by  Boye,  but  it  is  a 
rare  and  unique  discovery.2 


ii.,  XXXII.  355.  H.  Carvill  Lewis,  "The  Iron  Ores  of  the  Brandon  Pe- 
riod," Amer.  A.  A.  Sci.,  XXIX.  427,  1880.  J.  F.  Lewis,  "The  Hematite 
(Brown)  Ore  Mines,  etc.,  East  of  the  Hudson  River,"  M.  E.,  V.  216.  J.  G. 
Percival,  Rep.  on  the  Geol.  of  Conn.,  p.  132 ;  also,  Amer.  Jour.  Sci.,  ii., 
11.268.  R.  A.  F.  Penrose,  "Report  on  Manganese  Ores,"  Geol.  Survey 
Ark.,  1890,  Vol.  I.  (Contains  many  valuable  descriptions  of  Vermont 
limonites.)  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.  C.  N.  Shepard,  "No- 
tice, etc.,  of  the  Iron  Works  of  Salisbury,  Conn.,"  Amer.  Jour.  Sci.,  i., 
XIX-.  311.  J.  C.  Smock,  Butt.  Vll.  New  York  State  Museum,  pp.  12,  52. 
N.  H.  and  H.  V.  Winchell,  "  Taconic  Ores  of  Minnesota  and  Western  New 
England,"  Amer.  Geol.,  VI.  263.  1890. 

1  B.  T.  Putnam,  Tenth  Census,  Vol.  XX.,  p.  176.     See  also  Geol.  Sur- 
vey Neiv  Jersey,  1880. 

2  Dr.  Boye,  "Oxyd  of  Cobalt  with  the  Brown  Hematite  of  Chester 
Ridge,  Penn.,  Amer.  Phil.  Soc.,  January,  1846.     P.  Fraser,  Second  Geol. 
Survey  Penn.,  Reps.  C  and  CC  ;  "Origin  of  the  Lower  Silurian  Limonites 


82  KEMP'S   ORE  DEPOSITS. 

2.01.20.  The  Siluro-Cambrian  limonitesrun  across  Maryland  in 
Carroll   and  Frederick  counties,   and  are  mined  to   small  extent. 
(E.  R.  Benton,  Tenth  Census,  Vol.  XV.,  p.  254.) 

These  limonites  are  again  strongly  developed  in  the  Shenandoah 
Valley  along  the  western  base  of  the  Blue  Ridge,  and  in  south- 
western Virginia  in  the  Cripple  Creek  and  New  River  belt.  The 
ores  occur  in  connection  with  calcareous  shales,  calcareous  sand- 
stones, and  impure  limestones,  but  have  not  justified  the  expecta- 
tions formed  of  them.  In  Carroll  County,  Virginia,  the  gossan  of 
the  great  deposit  of  pyrite  is  dug  for  iron  ore.  The  walls,  however* 
are  older  than  the  Cambrian.1 

2.01.21.  The  limonites  of  eastern  Tennessee  are  the   southern 
prolongation  of  the  area  of  southwest  Virginia.     They  lie  between 
the  Archaean  of  the  Unaka  range  on  the  east,  and  the  Upper  Silurian 
strata  in  the  foot  of  the  Cumberland  tableland  on  the  west.     The 
ores  outcrop  in  the  longitudinal  valleys  or  "  coves."     The  bottoms 
of  these  valleys,  according  to  Safford  (p.  449),  are  formed  by  the 
shales,  slates,  and  magnesian  limestones  of  the  Knox  group,  and  in 

of  York  and  Adams  Counties,"  Proc.  Amer.  Phil.  Soc.,  March,  1875.  J.  W. 
Harden,  "  The  Brown  Hematite  Ore  Deposits  of  South  Mountain  between 
Carlisle,  Waynesborough,  and  the  Southeast  Edge  of  the  Cumberland  Val- 
ley," M.  E.,  I.  136.  J.  P.  Lesley,  Summary,  Final  Report,  Vol.  I.,  1892, 
pp.  205,  341.  Rec.  A.  S.  McCreath,  Second  Geol.  Survey  Penn.,  Vol. 
MM,  199.  F.  Prime,  Second  Geol.  Survey  Perm.,  Reps.  D  and  DD ;  "On 
the  Occurrence  of  the  Brown  Hematite  Deposits  of  the  Great  Valley, "• 
M.  F..,  III.  410  ;  Amer.  Jour.  Sci.,  ii.,  IX.  433  ;  also,  XL  62,  and  XV.  261. 
Rec.  B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  181. 

1  E.  R.  Benton,  Tenth  Census,  Vol.  XV.,  p.  261.  J.  L.  Campbell, 
"Report  on  the  Mineral  Prospects  of  the  St.  Mary  Iron  Property,"  etc., 
The  Virginias,  February,  1883,  p.  19.  See  also  The  Virginias,  January, 
1880,  p.  4  ;  March,  p.  43.  F.  P.  Dewey,  " The  Rich  Hill  Iron  Ores,"  M.  E., 
X.  77.  W.  M.  Fontaine,  "Notes  on  the  Mineral  Deposits  of  Certain  Lo- 
calities in  the  Western  Part  of  the  Blue  Ridge,"  Tlie  Virginias,  March, 
1883,  p.  44  ;  April,  p.  55  ;  May,  p.  73  ;  June,  p.  92.  B.  S.  Lyman,  "On  the 
Lower  Silurian  Brown  Hematite  Beds  of  America,"  A.  A.  A.  S.,  XVII. 
114.  A.  S.  McCreath,  "  The  Iron  Ores  of  the  Valley  of  Virginia,"  M.  E., 
XII.  103;  Engineering  and  Mining  Journal,  June,  1883,  p.  334.  E.  C.  Mox- 
ham,  "  The  Great  Gossan  Lead  of  Virginia,"  M.  E.,  February,  1892.  E.  C. 
Pechin,  "The  Iron  Ores  at  Buena  Vista,  Rockbridge  County,  Virginia," 
Engineering  and  Mining  Journal,  Aug.  3, 1889,  p.  92;  "Mining  of  Potsdam 
Brown  Ores  in  Virginia,"  Engineering  and  Mining  Journal,  Sept.  19, 1891, 
p.  337;  "  Iron  Ores  of  Virginia  and  Their  Developments,"  M.  E.,  XIX.  101 ; 
"Ore  Supply  for  Virginia  Furnaces,"  Engineering  and  Mining  Journal, 
Vol.  LI.,  1891,  pp.  322,  349.  Rec. 


I 


84  KEMP'S   ORE  DEPOSITS. 

the  residual  clay  left  by  their  alteration  the  ore  is  found.  The  gos- 
san of  the  neighboring  veins  of  copper  pyrites,  best  known  at  Duck- 
town  (see  Example  16),  were  originally  exploited  for  iron.1 

The  Tennessee  limonite  extends  across  northwestern  Georgia, 
and  still  farther  east  the  Huronian  limestones  of  North  Carolina 
also  enter  the  State.  But  as  even  these  Huronian  schists  and  as- 
sociated marbles  have  been  considered  by  F.  P.  Bradley  to  be 
metamorphosed  Silurian  (Cambrian),  the  ores  may  also  belong  un- 
der Example  2a.  The  well-determined  Siluro-Cambrian  rocks 
form  but  a  narrow  belt  of  no  great  importance  in  North  Carolina.2 

The  limonites  are  again  strongly  developed  in  Alabama  and 
furnish  a  goodly  proportion  of  the  ore  used  in  the  State.  They 
form  a  belt  lying  east  of  the  Clinton  ores  (Example  6),  later  de- 
scribed. As  in  Tennessee,  they  are  associated  with  strata  of  the 
Knox  group.3 

2.01.22.  Extensive  deposits  of  limonite  also  occur  in  the  Lake 
Superior  district,  near  Negaunee,  Mich.,  as  stated  above,  but  they 
are  mentioned  again  under  Example  9a.     They  are  in  Huronian 
strata. 

2.01.23.  Origin  of  the  Siluro-  Cambrian  Limonites. — Dr.  Jack- 
son of  the  First  Pennsylvania  Survey  argued  in  1839*  that  they 
originated  in  situ  ;  that  is,  by  the  alteration  of  the  rocks  in  and 
with  which  they  occur.     Percival,  in  his  report  on  the  Geology  of 
Connecticut,  in  1842  (p.  132)  attributed  them  to  the  alteration  of 
pyrite   in   the   neighboring  mica-slate.      Prime,  in  Pennsylvania, 
in  1875  and  1878  (Reports  D  and  DD),  considers  that  the  iron  has 
been  obtained  by  the  leaching  of  the  neighboring  dolomites  and 
slates,  it  being  in  them  either  as  silicate,  carbonate,  or  sulphide  ; 
that  the  ore  has  reached  its  position  associated  with  the  slates,  be- 
cause, being  impervious,  they  retained  the  ferruginous  solutions ; 
and  that  the  potash  abundantly  present  in  the  slates  probably  as- 
sisted in  precipitating  it.5    Frazer,  in  1876,6  in  studying  the  beds  of 

1  J.  M.  Safford,  Geol.  of  Tenn  ,  p.  448,  1869.    B.  Willis,  Tenth  Census, 
Vol.  XV.,  p.  331. 

2  F.  P.  Bradley,  "  The  Age  of  the  Cherokee  County  Rocks,  North 
Carolina,"  Amer.  Jour.  Sci.,  iii.,  IX.  279  and  320;  B.  Willis,  Tenth  Cen- 
sus, Vol.  XV.,  p.  367. 

3  W.  M.  Chauvenet,  Tenth  Census,  Vol.  XV.,  p.  383.     For  other  ref- 
erences to  Alabama  iron  ore  deposits,  see  under  Example  6. 

4  Ann.  Rep.  First  Penn.  Survey,  1839. 

5  M.E.,  II.  410. 

6  Second  Penn.  Survey,  Rep.  C,  p.  136. 


THE  IRON  SERIES  (IN  PART).  85 

York  and  Adains  counties,  Pennsylvania,  found  the  hydromica 
slates  filled  with  the  casts  of  pyrite  crystals,  and  held  these  to 
have  been  the  sources  of  the  iron,  by  affording  ferrous  sulphate 
and  sulphuric  acid.  The  latter  reacted  on  the  alkali  of  the  slates, 
producing  sodium  sulphate.  This,  meeting  calcium  carbonate,  af- 
forded calcium  sulphate  and  sodium  carbonate,  which  later  precipi- 
tated the  iron.  Calcium  carbonate  alone  is,  however,  abundantly 
able  to  precipitate  iron  carbonate  and  oxide  from  both  ferrous  and 
ferric  sulphate  solutions  (even  when  natural)  without  the  intro- 
duction of  the  alkali,  although  this  might  account  for  the  alteration 
of  the  slates.1 

2.01.24.  J.  D.  Dana  has  written  at  length  on  the  New  England 
and  New  York  deposits,  and  finds  them  always  at  or  near  the  junc- 
tion of  a  stratum  of  limestone,  proved  in  many  cases  to  be  ferrif- 
erous, and  sometimes  entirely  siderite,  and  one  of  hydromica 
slate  or  mica  schist.  In  several  mines  bodies  of  unchanged  spathic 
ore  are  embedded  in  the  limonite.  Hence  Professor  Dana  explains 
the  limonite  as  derived  by  the  weathering  of  a  highly  ferruginous 
limestone,  from  which  the  limonite  has  been  left  behind  by  the 
removal  of  the  more  soluble  elements,  so  as  practically  to  replace 
the  limestone  in  connection  with  other  less  soluble  matter.  The 
limonite  has  also  at  times  replaced  the  schists,  probably  deriving 
its  substance  in  part  from  iron-bearing  minerals  in  them,  and 
changing  these  rocks  to  the  ochers  and  clays  now  found  with  the 
ores.  These  views  are  undoubtedly  very  near  the  truth  for  the 
region  studied.  (Cf.  also  Example  4.)  Weathering  limestones  do 
furnish  residual  clay  ocher,  etc.,  as  is  shown  by  the  deposits  of 
western  Kentucky  and  Tennessee  under  Example  2. 

2.0  .25.  Another  hypothesis  early  formulated  and  advocated 
by  many  is  that  the  limonites  have  been  derived  by  the  surface 
drainage  of  the  old  Appalachian  highlands  and  then  precipitated  in 
still  water  where  they  are  now  found.  A  precipitation  around  the 
shores  of  a  ferruginous  sea  has  also  been  urged  on  the  analogy  of 
certain  explanations  of  the  Clinton  ore.  (Example  6.)  Their  sup- 
posed Tertiary  age  has  already  been  remarked.  All  these  views  are 
essentially  hypothetical.2 

1  See  F.  P.  Dunnington,  "  On  the  Formation  of  Deposits  of  Manga- 
nese," Amer.  Jour.  Sci.,  iii.,  XXXVI.,  p.  175.  (Experiments  10  and  11.) 

3  See  H.  D.  Rogers,  Trans.  Asso.  Amer.  Qeol.  and  Nat.,  1842,  p.  345 ; 
E.  Hitchcock,  Geol.  Vt.,  Vol.  I.,  p.  233  ;  J.  P.  Lesley,  Iron  Man.,  p.  501  ; 
Rep.  A,  Second  Penn.  Survey,  p.  83  ;  J.  S.  Newberry,  International  Re- 
view, November  and  December,  1874. 


86 


KEMPS   ORE  DEPOSITS. 


ANALYSES    OF    LIMONITES. 

2.01.26.  All  published  analyses,  except  when  forming  a  suffi- 
ciently large  and  continuous  series  from  the  output  of  any  one  mine, 
are  to  be  taken  with  caution.  Ores  necessarily  vary  much,  and  a 
single  analysis  or  a  selected  set  may  give  a  very  wrong  impression. 
The  percentage  in  iron  is  different  for  different  parts  of  the  same 
ore  body.  The  few  that  follow  have  been  selected  to  show  the 
range  and  the  average.  The  highest  are  exceptionally  good,  the 
lowest  less  than  the  average,  and  the  medium  values  indicate  ap- 
proximately the  general  run.  Limonites  afford  from  40  to  50g  Fe 
as  actually  exploited,  but  it  is  not  difficult  to  find  individual  analy- 
ses that  run  higher.  They  are  not,  generally  speaking,  Bessemer 
ores. 

Analyses  of  Limonites. 


Fe. 

P. 

S. 

SiO2 

A1S0, 

H20. 

Berkshire  County,  Mass.       .... 

47.52 

0.187 

Connecticut 

50  48 

0  353 

Dutchess  County  New  York  .  .  . 

46  45 

0  370 

14  10 

3  053 

Staten  Island  
Pennsylvania 

39.72 
56  3 

0.05*) 
0  125 

0.391 
0  02 

14.19 
5  165 

3.59 

12.41 

"Virginia/  (Low  Moor)       . 

43  34 

0  636 

Tennessee  (Lagrange  Furnace)  
Alabama  .... 

50.91 
50  89 

0.237 
0  225 

Colorado  

53  37 

0.034 

0.20 

7.90 

0.70 

Colorado  avera/fire 

43  00 

0  030 

20 

13. 

Prosser  mine  Oregon 

44  71 

0  666 

Pure  mineral  .*  

59  92 

14.4 

SIDERITE,   OR  SPATHIC  ORE. 

2.01.27.  Siderite  is  the  protocarbonate  of  iron.     As  a  mineral 
it  often  contains  more  or  less  calcium,  magnesium,  and  manganese. 
When  of  concretionary  structure,  embedded  in  shales  and  contain- 
ing much  clay,  the  ore  is  called  clay  ironstone.     When  the  concre- 
tions enlarge  and  coalesce,  so  as  to  form  beds  of  limited  extent, 
generally   containing  much  bituminous    matter,    they    are    called 
black-band,   and  are   chiefly  developed   in  connection   with    coal 
seams. 

2.01.28.  Example  3.     Clay  Ironstone. — The  name  is  applied  to 
isolated  masses  of  concretionary  origin  (kidneys,  balls,  etc.)  which 
may  at  time  coalesce  to  form  beds  of  considerable  extent.     They 
are  usually  distributed  through  shales,  and  on  the  weathering  of 
the  matrix  are  exposed  and  concentrated.     They  are  especially 


THE  IRON  SERIES  (IN  PART).  87 

characteristic  of  Carboniferous  strata  and  differ  from  black-band 
only  in  the  absence  of  bituminous  matter  and  in  the  consequent 
drab  color.  They  weather  to  liinonite,  generally  in  concentric  shells 
with  a  core  of  unchanged  carbonate  within.  Fossil  leaves  or  shells 
often  furnish  the  nucleus  for  the  original  concretion,  and  are  thus, 
as  at  Mazon  Creek,  111.,  beautifully  preserved.  When  in  beds  the 
ore  is  sometimes  called  flagstone  ore;  when  broken  into  rectangular 
masses  by  joints,  it  is  called  block  ore. 

2.01.29.  Example  3a.     Slack-band. — The  name  is  applied  to 
beds  consisting  chiefly  of  carbonate  of  iron  with  more  or  less  earthy 
and  bituminous  matter.     They  are  of  varying  thickness,  though 
rarely  more  than  six  feet,  and  are  almost  invariably  associated 
with  coal  seams.     They  are  thus  especially  found  in  the  Carbonif- 
erous system,  and  to  a  far  less  degree  in  the   eastern  Jura-Trias. 
They  are  also  recorded  with  the  Cretaceous  coals  of  the  West.     It 
is  not  possible  to  separate  the  two  varieties  in  discussing  their  dis- 
tribution.    The  various  productive   areas  are  taken  up  geograph- 
ically, beginning  with  the  Appalachian  region. 

2.01.30.  The  carbonate  ores  are  of  great  importance  in  the 
Carboniferous  of  western  Pennsylvania  and  in  the  adjacent  parts  of 
Ohio,  West  Virginia,  and  Kentucky.    In  these  States  the  system  is 
subdivided  in  connection  with  the  coal,  from  above  downward,  as 
follows  :   I.  The  Upper  Barren  Measures,  Permo-Carboniferous,  or 
Dunkard's  Creek  Series  ;  II.  The  Upper  Productive  Coal  Meas- 
ures, or  Monongahela  River  Series  ;  III.  The  Lower  Barren  Meas- 
ures,  or   Elk   River   Series ;     IV.    The   Lower    Productive    Coal 
Measures,  or  Alleghany  River  Series  ;    V.  The  Great  or  Pottsville 
Conglomerate.     In  the  Upper  Barren  Measures  of  Pennsylvania, 
according  to  McCreath,  there  is  hardly  a  stratum  of  shale  or  sand- 
stone without  clay  ironstone  nodules,  but  no  continuous  beds  are 
known.1     The  deposits  are  not  of  great  actual  importance,  and  are 
worthy  of  only  passing  mention.     In  the  Upper  Productive  Coal 
Measures  some  ore  occurs  associated  with  the  Waynesburg  Coal 
seam,  and  again,  just  under  the  Pittsburg  seam,  there  is  consider- 
able known  as  the  Pittsburg  Iron  Ore  Group.     This  latter  ore  be- 
comes of  great  importance  in  Fayette  County  and  extends  through 
several  tfeds.2     The  Lower  Barren  Measures  in  Pennsylvania  also 
contain  carbonate  ore  in  a  number  of  localities.     The  most  per- 

1  Second  Penn.  Survey,  Rep.  K,  p.  386  ;  MM,  p.  159. 

2  Rep.  MM,  p.  162 ;  KK,  p.  Ill ;  L,  p.  98. 


88  KEMP'S   ORE  DEPOSITS. 

sistent  is  the  Johnstown  ore  bed,  near  the  base  of  the  series.    There 
are  two  additional  beds  just  over  the  Mahoning  sandstone. 

The  Lower  Coal  Measures  are  the  chief  ore  producers  in  all  the 
States.  They  furnish  balls  of  clay  ironstone  in  very  many  localities 
in  western  Pennsylvania,  which  will  be  found  recorded  with  many 
additional  references  in  Report  MM,  p.  1*74,  Penn.  GeoL  Survey. 
The  nodules  are  scattered  through  clay  and  shales.  The  so-called 
Ferriferous  Limestone,  which  lies  a  few  feet  below  the  Lower  Kit- 
taning  Coal  Seam,  affords  in  its  upper  portion  varying  thicknesses 
of  carbonate  ore,  known  as  "  buhrstone  ore,"  which  is  altered  in 
large  part  to  limonite.  Some  little  carbonate  ore  was  found  in 
the  early  days  in  the  anthracite  measures  of  eastern  Pennsylvania. 
Several  beds  of  the  same  occur  in  the  Great  Conglomerate  and 
its  underlying  (Mauch  Chunk)  shales.  They  are  chiefly  developed 
in  southwestern  Pennsylvania  (Report  KK),  and  may  form  either 
entire  beds  or  disseminated  nodules.  The  limonites  of  the  Mar- 
cellus  stage  that  pass  into  carbonate  in  depth  in  Perry  and  the 
neighboring  counties  have  already  been  mentioned  under  Example 
2.  In  West  Virginia  both  Upper  and  Lower  Measures  afford  the 
ore.  From  the  latter  black-band  is  extensively  mined  on  Davis 
Creek,  near  Charleston.1 

2.01.31.  In  Ohio  a  number  of  nodular  deposits  are  known,  but 
practically  no  ore  is  produced  above  the  Mahoning  sandstone  of 
the  Lower  Coal  Measures.     Below  this  sandstone  the  ores  are  ex- 
tensively developed.     They  extend  up  and  down  the  eastern  part 
of  the  State  and  are  both  black-band  and  clay  ironstone.     Orton 
identifies  twelve  different  and  well-marked  horizons  distributed 
through  the  Lower  Measures.     He  distinguishes  the  stratified  ores 
mostly  black-band,  and  the  concretionary  ores,  including  kidney 
ores,  block  ores,  and  limestone  ores.2 

2.01.32.  The  general  distribution  of  the  iron  ores  of  Kentucky 
has  already  been  outlined  under  Example  2.     The  Hanging  Rock 
region  is  a  southern  prolongation  of  the  Ohio  district  of  the  same 
geological  horizon.     P.  X.  Moore  has  classified  the  local  ores  as 
limestone  ores  which  are  associated  with  limestone,  block  ores,  and 
kidney  ores.     The  last  two  names  refer  to  the  fracture  or  shape  of 


1  M.  F.  Maury  and  W.  M.  Fontaine,  Resources  of  West  Virginia,  1876, 
p.  247. 

8  Geol.  of  Ohio,  V,  p.  378,  and  supplemental  report  on  the  Hanging 
Rock  region  in  Vol.  III. 


THE  IRON  SERIES  (IN  PART).  89 

the  masses.  They  occur  associated  with  the  usual  clay  and  shale. 
Farther  west,  between  the  Kentucky  and  Red  rivers,  are  the 
other  deposits,  the  principal  one  of  which  comes  low  in  the  series, 
just  over  the  Subcarboniferous  limestone.1 

2.01.33.  Small  quantities  of  black-band  have  been  found  in  the 
Deep  River  coal  beds,  in  North  Carolina,  associated  with  the  Tri- 
assic  coals.2 

A  large  bed,  or  series  of  beds,  has  recently  been  reported  from 
Enterprise,  Miss.,  in  strata  of  the  Claiborne  stage.  They  run  from 
ten  to  eighteen  feet  in  thickness  and  extend  for  miles.3  Scattered 
nodules  have  been  noted  at  Gay  Head,  Martha's  Vineyard.4  Car- 
bonate ores  are  as  yet  of  no  importance  in  the  coal  measures  of  the 
Mississippi  Valley.  They  have  been  found  associated  with  the 
Cretaceous  coals  of  Wyoming  and  Colorado, — and  indeed  the  first 
pig  iron  of  the  latter  State  was  made  from  them  in  Boulder 
County, — but  they  are  not  an  important  source  of  ore.5  An  ex- 
tended bed  of  very  excellent  carbonate  has  recently  been  discov- 
ered with  coal  near  Great  Falls,  in  the  Sand  Coulee  region  of 
Montana.  Being  near  coal,  limestone,  and  other  iron  ores,  it  prom- 
ises to  be  of  considerable  importance.6 

2.01.34.  Example  4.      Burden  Mines,    near   Hudson,   N.   Y. 
Elongated  lenticular   beds   of   clay   ironstone,  passing   into    sub- 
crystalline  siderite,  inclosed  conformably  between  underlying  slates^ 
and  overlying  calcareous  sandstone,  of  the  Hudson  River  stage. 
The  ore  occurs  in  four  "basins,"  which  outcrop  along  the  western 
slope  of  a  series  of  moderate  hills,  just  east  of  the  Hudson  Riv- 
er.     The   hills  have  been  shown  by  Kimball  to  be  the  eastern 
halves  of  anticlinal  folds  now  reduced  by  erosion  to  easterly  dip- 
ping monoclines.     The  western  half  of  the  ore  bodies  has  been 
eroded  away,  leaving  an  outcrop  forty-four  feet  thick  as  a  maxi- 
mum, which  pinches  out  along  the  strike  and  dip.     The  basins  ex- 

1  P.  N.  Moore,  "On  the  Hanging  Rock  District  in  Kentucky,"  Ken- 
tucky Geol.  Survey,  Vol.  I.,  Part  3. 

2  B.  Willis,  Tenth  Census,  Vol.  XV.,  p.  306  ;  W.  C.  Kerr,  Geology  of 
North  Carolina,  1875,  p.  225. 

3  A.  F.  Brainard,  "  Spathic  Ore  at  Enterprise,  Miss.,"  M.  E.,  XIV.  146. 

4  W.  P.  Blake,  "Notes  on  the  Occurrence  of  Siderite  at  Gay  Head, 
Mass.,"  M.  E.,  IV.  112. 

5  R.  Chauvenet,  "Notes  on  the  Iron  Resources  of  Colorado,"  Ann* 
Rep.  Colo.   School  of  Mines,  1885,  1886 ;  Trans.  Amer.  Inst.  Min.  Eng.> 
Colorado  meeting,  1889. 

6  O.  C.  Mortson,  Mineral  Resources  U.  S.,  1888,  p.  34. 


KEMP'S   ORE  DEPOSITS. 


tend  from  southwest  to  northeast,  parallel  to  the  trend  of  the  hills. 
The  beds  are  more  or  less  faulted.  The  southern  part  of  the  second 
basin  affords  Bessemer  ores,  but  the  others  are  too  high  in  phos- 
phorus. At  this  point  the  principal  mining  has  been  done.  Ac- 


§ 

f 


cording  to  Olmstead,  some  varieties  are  richer  in  phosphorus  than 
others,  but  they  are  so  intimately  mixed  as  not  to  be  practicably 
separated.  Up  to  1889  the  mines  had  produced  450,000  tons  of 
roasted  Bessemer  ores. 


THE  IRON  SERIES  (IN  PART).  91 

2.01.35.  In  their  geological  relations  the  ores  are  of  the  greatest 
interest,  as  they  occur  on  the  western  limit  of  the  metamorphic  belt, 
which  forms  the  basis  of  the  Taconic  controversy,  yet  in  strata 
which  have  been  identified  by  fossils.     Beds  of  limonite  hitherto 
regarded  as  Siluro-Cambrian  occur  to  the  east ;  and  should  further 
study,  on  the  lines  developed  chiefly  by  J.  D.  Dana,  W.  B.  Dwight, 
and  C.  D.  Walcott,  clear  up  their  stratigraphical  relations,  the 
work  done  in  developing  the  structure  of  the  siderite  basins,  as 
pointed  out  by  Kimball,  may  be  of  great  aid  in  explaining  them. 
Very  similar  bodies  of  siderite  occur  with  these  limonites.     (Ex- 
ample 2a.)     The  Burden  ores  are  relatively  high  in  magnesia,  and 
this  leads  Kimball  to  suggest  their  original  deposition  from  the 
off-shore  drainage  of  the  basic  rocks  of  the  Archaean  highlands. 
Further,    it    may   be    added    that    the    ores    in    their   lenticular 
shape  are  highly  suggestive  of  a  possible  origin  for  magnetite  de- 
posits, and  they  are  again  referred  to  under  "  Magnetite."     Other 
deposits  of  siderite  in  the  shales  of  the  Marcellus  stage  are  known 
and  were  formerly  worked  at  Wawarsing,  Ulster  County,  across 
the  Hudson  River.1 

2.01.36.  Example  5.    Roxbury,  Conn.    A  fissure  vein  in  gneiss, 
six  to  eight  feet  wide,  of  crystalline  siderite,  with  which  are  as- 
sociated quartz  and  a  variety  of  metallic  sulphides,  galena,  chal- 
copyrite,  zincblende,  etc.     Although  productive  in  former  years,  it 
is  no  longer  worked,  and  is  of  scientific  more  than  economic  inter- 
est, being  a  unique  deposit.     It  has  furnished  many  fine  cabinet 
specimens.2 

1  J.  P.  Kimball,  "  Siderite  Basins  of  the  Hudson  River  Epoch,"  Amer. 
Jour.  Sci.,  III.,  xl.  155.    I.  Olmstead,  "Distribution  of  Phosphorus  in  the 
Hudson  River  Carbonate,"  M.  E.,  1889.     R.  W.  Raymond,  "The  Spathic 
Ores  of  the  Hudson  River,"  M.  E.,  IV.  309.    J.  C.  Smock,  Bulletin  of  New 
York  State  Museum  on  Iron  Ores,  p.  62. 

2  J.  P.  Lesley,  Iron  Manufacturers'1  Guide,  p.  649.    C.  U.  Shepherd, 
"  Report  on  the  Geology  of  Connecticut,"  1837,  p.  30,  Amer.  Jour.  Sci.,  L, 
xix.  311. 


CHAPTER  II. 

THE  IRON  SERIES  CONTINUED.— HEMATITE,   RED  AND 
SPECULAR. 

2.02.01.  The  sesquioxide  of  iron,  F2O3,  is   always   of   a   red 
color  when  in  powder.     If  it  is  of  earthy  texture,  this  color  shows 
in  the  mass,   and  the  ore  is  called  red   hematite  ;    if  the  ore  is 
crystallized,  the  red  color  is  not  apparent,  and  the  brilliant  luster  of 
the  mineral  gives  it  the  name  specular  hematite.    The  red  hematites 
are  first  treated. 

2.02.02.  Example  6.      Clinton    Ore. — Wherever  the   Clinton 
stage  of  the  Upper  Silurian  outcrops,  it  almost  invariably  contains 
one  or  more  beds  of  red  hematite,  interstratified  with  the  shales 
and  limestones.     These  ores  are  of  extraordinary  persistence,  as 
they  outcrop  in  Wisconsin,  Ohio,  and  Kentucky  in  the  interior,  and 
then  beginning  in  New  York,    south  of  Lake  Ontario,  they  run 
easterly  across  the  State.     Again  in  Pennsylvania  they  follow  the 
waves   of   the  ,  Appalachian   folds,  and   extend   south   into  West 
Virginia  and  Virginia  in  great  strength.     They  are  found  in  east- 
ern Tennessee  and  northwestern  Georgia,  and  finally  in  Alabama  are 
of  exceptional  size  and  importance.    The  structure  of  the  ore  varies 
somewhat.     At  times  it  is  a  replacement  of  fossils,  such  as  crinoid 
stems,  molluscan  remains,  etc.  (fossil  ore)  ;  again  as  small  oolitic 
concretions,  like  flaxseed  (flaxseed  ore,  oolitic  Ore,  lenticular  ore)  ; 
while  elsewhere  it  is  known  as  dyestone  ore.     The  ore  in  many 
places  is   really  a  highly  ferruginous   limestone,  and  below   the 
water  level  in  the  unaltered  portion  it  often  passes  into  limestone, 
while  along  the  outcrop  it  is  quite  rich. 

2.02.03.  In  Dodge  County,  southeastern  Wisconsin,  the  ore  is 
14  to  26  feet  thick  and  consists  of  an  aggregate  of   small  len- 
ticular grains.1     In  Ohio  it  outcrops    in  Clinton,  Highland,   and 

1  T.  C.  Chamberlain,  Geol  Survey  Wis.,  Vol.  L,  p.  179.  R.  D.  Irving, 
"  Mineral  Resources  of  Wisconsin,"  M.  E.,  VIII.  478;  Geol.  Survey  Wis., 
Vol.  L,  p.  625. 


THE  IRON  SERIES   CONTINUED.  i»3 

Adams  counties,  in  the  southwestern  portion  of  the  State  along  the 
flanks  of  the  Cincinnati  Arch,  but  it  is  thin  and  poor  in  iron,  al- 
though rich  in  fossils.1  A  small  area  of  the  Clinton  has  furnished 
considerable  ore  in  Bath  County,  Kentucky,  where  it  is  altered  to 
limonite.3 

2.02.04.  Coming  eastward,  the  limestones  and  the  shales  of  the 
Clinton  outcrop  in  the  Niagara  River  gorge  in  New  York,  but  show 
no  ore.  This  appears  first  in  quantity  in  Wayne  County,  a  hundred 
miles  east  and  just  south  of  Lake  Ontario.  One  bed  reaches  20  to 
22  inches.  Farther  east  are  the  Sterling  mines,  in  Cayuga  County  ; 
and  again  near  Utica,  in  the  town  of  Clinton,  which  first  gave  the 
ore  its  name,  it  is  of  great  economic  importance.  There  are  two 


cP    <3 

'.>5,.     THMO'± 


=  -•= — ~— =-—Tr-     Shale  ? 


Limestone  0-6 


FIG.  12. — Clinton  Ore,  Ontario,  Wayne  County,  New  York.    After 
C.  H.  Smyth,  Jr. 

workable  beds,  the  upper  of  which,  with  a  thickness  of  about  two 
feet,  is  the  only  one  now  exploited.  Beneath  this  are  12  or  15 
inches  of  shale,  and  then  the  second  bed  of  8  inches  of  ore.3  Some 
25  feet  over  the  upper  bed  is  still  a  third,  which  is  too  low  grade 
for  mining.  It  is  four  to  six  feet  thick,  and  is  locally  called  red 
flux.  It  consists  of  pebbles  and  irregular  fragments  of  fossils, 
which  are  coated  with  hematite  and  cemented  with  calcite. 

2.02.05.  The  rocks  of  the  Clinton  thicken  greatly  in  Pennsyl- 
vania and  run  southwestward  through  the  central  part  of  the  State. 

1  J.  S.  Newberry,  Oeol.  of  Ohio,  Vol.  III.,  p.  7.  E.  Orton,  Oeol.  of 
Ohio,  Vol.  V.,  p.  371. 

8  N.  S.  Shaler,  Geol.  of  Ky.,  Vol.  III.,  163. 

8  A.  H.  Chester,  "The  Iron  Region  of  Central  New  York;"  address 
before  the  Utica  Merchants  and  Manufacturers'  Association,  Utica,  1881. 
J.  C.  Smock,  Bull,  of  N.  Y.  State  Museum.  C.  H.  Smyth,  Jr.,  "On  the 
Clinton  Iron  Ore,"  Amer.  Jour.  Sci.,  June,  1892,  p.  487. 


KEMP'S    ORE  DEPOSITS. 


Six  different  ore  beds  have  been  recognized,  of  which  the  lower  are 
probably  equivalent  to  the  southern  dyestone  ores.1 

The  ores  are  of  chief  importance  in  the  Juniata  district.  The 
belt  extends  south  west  ward  across  Maryland  and  eastern  West 
Virginia,  where  the  beds  are  quite  thick,  although  as  yet  not  much 
developed,  and  appears  in  the  extreme  southwest  corner  of  Virginia. 
Thence  it  runs  across  eastern  Tennessee,  and  is  of  very  great  ini- 


Calcareous  Sandstone 

and  , 

thin  Shale  layers    FO-f- 


Non-Oolitic  Ore    i 
(Red  Flux)       6 


Calcareous        , 
Sandstone      6 


Blue  Shale 

and  thin  , 

Sandstone  layers   15' 


Oolitic  Ore  2 

Shale    2'      , 
Oolitic  Orel 
Blue  Shal.e 
and  th'r.n 


—  anu  iiiii.il  i   t 

-g^zj^t^gr*!'-! .- 1 r^=\  Sandstone  layers   100  ± 

FIG.  IS.— Clinton  Ore,  Clinton,  New  York.    After  C.  H.  Smyth,  Jr. 

portance.  The  lines  of  outcrop  are  known  as  "dyestone  ranges." 
They  lie  west  of  the  Siluro-Cambrian  limestones  (Example  2a)  and 
in  the  edges  of  the  Cumberland  tableland.  Four  or  five  are 
known,  of  which  the  largest  extends  across  the  State.  This  ore  is 

1  J.  H.  Dewees,  "Fossil  Ores  of  the  Juniata  Valley,"  Penn.  Geol. 
Survey,  Rep.  F.  E.  d'Invilliers,  Ibid.,  Rep.  F3  (Union,  Snyder,  Mifflin, 
and  Juniata  counties).  A.  S.  McCreath,  Ibid.,  Rep.  MM,  p.  231.  J.  J. 
Stevenson,  Ibid.,  Reps.  MM  and  T2  (Bedford  and  Fulton  counties).  I.  C. 
White,  Ibid.,  Reps.  MM  and  T3  (Huntington  County).  H.  H.  Stock,  "  Ores 
at  Danville,  Montour  County,"  M.  E.,  October,  1891. 


THE  IRON  SERIES  CONTINUED. 


95 


more  fossiliferous  toward  the  south  and  more  oolitic  toward  the  / 
north.     It  is  very  productive  in  the  Chattanooga  region.1 

2.02.06.    The  Clinton  just  appears  in  northwestern  Georgia,  and 
continues  thence  into  Alabama,where  it  is  again  of  great  importance,, 


FIG.  14. — Clinton  Ore,  Eureka  Mine,  Oxmoor,  Ala.     After  C.  H.  Smyth,  Jr. 

and,  with  the  less  productive  Siluro-Cambrian  limonites,  furnishes 
practically  all  the  ore  of  the  State.  The  outcrop  can  be  traced 
almost  continuously  for  130  miles.  The  ore  is  rich  in  fossils  and 
occurs  in  several  beds,  which,  although  averaging  much  less,  may 


FIG.  15. — Cross-section  of  the  Sloss  Mine,  Red  Mountain,  Ala. 

aggregate,  as  at  the  Eureka  furnace,  as  much  as  34  to  37  feet.  The 
chief  mines  are  in  Red  Mountain,  a  northeast  and  southwest  ridge, 
east  and  south  of  Birmingham.  Folds  and  faults  have  brought  the 
beds  into  close  proximity  with  the  coal  and  limestone  of  the 
region,  and  thus  into  a  position  very  favorable  for  economic 
working.2 

1  Killebrew  and  Safford,  Resources  of  Tennessee.     E.  C.  Pechin,  "  The- 
Iron  Ores  of  Virginia,"  etc.,  M.  E.,  XIX  1016.     J.  B.  Porter,  "  Iron  Ores,, 
Coal,  etc.,  in  Alabama,  Georgia,  and  Tennessee,"  M.  E.,  XV.  170.    J.  M. 
Safford,  Geol.  of  Tenn. 

2  A.  F.  Brainerd,  "  On  the  Iron   Ores,  Fuels,  etc.,   of  Birmingham, 


FIG.  16. — Map  of  the  Vicinity  of  Birmingham,  Ala.    From  the  Transac- 
tions of  the  American  Institute  of  Mining  Engineers,  Vol.  XIX., 

Plate  IV. 


THE  IRON  SERIES,    CONTINUED.  97 

2.02.07.  Red  hematite,  supposed  to  be  of  the  Clinton  stage,  oc- 
curs in  Nova  Scotia  in   very   considerable  amount,  in  Pictou   and 
Antigonisli  counties.1 

2.02.08.  In  general  the  Clinton  ore  is  characterized  by  a  high 
percentage  of  phosphorus,  and  is  seldom,  if  ever,  available  for  Bes- 
semer pig.    It  is  chiefly  employed  for  ordinary  foundry  irons.    The 
percentage  in  iron  varies  much.     Experience  at   Clinton,   K.  Y., 
shows  that  it  averages  about  44$  Fe  in  the  furnace.     These  hema- 
tites have  undoubtedly  originated  in  some  cases  by  the  weathering 
of  ferruginous  limestones  above  the  water  level.     I.  C.  Russell  has 
shown  that  the  unaltered  limestones  at  the  bottom  of  a  mine  in 
Atalla,  Ala.,  250  feet  from  the  surface,  contained  but  7.75$   Fe, 
while  the  outcrop  afforded  57.52$.     J.  B.  Porter  has  recorded  the 
gradual  increase  of  lime  also  in  another  Alabama  mine,  from  a 
trace  at  the  outcrop  to  30.55$  at  135  feet.    Other  writers  have  ex- / 
plained  these  beds  as  due  to  the  bringing  of  iron  in  solution  into( 
the  sea  of  the  Clinton  age  and  to  its  deposition  as  small  nodules, 
etc.,  or  as  ferruginous  mud.     (Roger,  Lesley,  Newberry.)     In  this 
way   an  oolitic  mass  has  originated,  as  in  the   modern  Swedish 
lakes  (Xe  wherry).    (See  Example  1.)     N.  S.  Shaler  has  argued,  on 
the  basis  of  the  Kentucky  beds,  that  the  iron  has  been  derived  from 
the  overlying  shales,  and  descending  in  solution  has  been  precipi- 
tated by  the  lower  lying  limestones.     As  the  shales  are  themselves 
calcareous,  this  seems  improbable.     A.  F.  Foerste  has  shown  that 
the  ore  is  very  often  deposited  either  in  the  interstices  of  frag-, 
ments  of  bryozoans  or  as  replacing  their  substance.     The  rounded, 
water-worn  character  of  the  original  fragments  is  regarded  as  oc- 
casioning the  apparent  concretionary  character.    Admirable  work 
upon  the  origin  of  the  ore  has  also  been  done  by  C.  II.   Smyth, 
Jr.     He  finds  that  the  small  oolites,  or  concretions,  as  they  occur 
at  Clinton,  N.  Y.,   and  many  other  localities,  have  a  water-worn 
grain  of  quartz  as  a  nucleus.     The  character  of  the  grain  is  such 
that  it  has    evidently  been  derived  from   granitoid  or  schistose 
rocks.     The  hematite  comes  off  at  times  in  concentric  layers,  when 

Ala.,"  M.  #.,  XVII.  151.  "The  Sloss  Iron  Ore  Mines,"  Engineering  and 
Mining  Journal,  Oct.  1,  1892,  p.  318.  T.  S.  Hunt,  ".  Coal  and  Iron  in  Ala- 
bama," M.  E.,  XI.  236.  J.  B.  Porter,  "  Iron  Ores,  Coal,  etc.,  in  Alabama, 
Georgia,  and  Tennessee,"  M.  E.,  XV.  170.  E.  A.  Smith,  Alabama  Geol. 
Survey,  1876  ;  also  A.  A.  A.  S.,  XXVII.  246. 

1  Sir  J.  W.  Dawson,  Acadian  Geology,  p.  591.     Fletcher,  Can.  Geol. 
Survey,  1886. 


98  KEMP'S  ORE  DEPOSITS. 

tapped  gently.  It  may  also  be  dissolved  away  so  as  to  leave  a. 
siliceous  cast  or  skeleton  of  the  spherule.  Dr.  Smyth  thus  makes  a 
strong  argument  that  the  ores  in  such  cases  are  concretionary,  and 
that  they  were  formed  in  shallow  waters  around  the  nuclei  of  sand. 
But  he  also  admits,  as  others  quoted  above  have  indicated,  that  the 
replacement  of  bryozoa  and  the  weathering  of  ferruginous  lime- 
stone have  in  many  localities  played  their  part.  The  iron  ore  is  in 
the  latter  case  a  residual  product,  but  now  the  mine  waters  are  de- 
positing calcium  carbonate  rather  than  removing  it.1 

2.02.09.  Glenmore  Estate,  Greeribrier  County, West  Virginia.  A 
bed  of  red  hematite  in  Oriskany  sandstones.  Limonites  are  abundant 
in  the  Oriskany  of  Virginia,  and  the  hematite  may  have  been  de- 
rived from  such  2  or  vice  versa. 

2.02.10.  Mansfield  Ores,  Tioga  County,  Pennsylvania.     Three 
beds  of  ore  are  found  in  the  strata  of  the  Chemung  stage  of  Tioga 
County,  Pennsylvania.     They  are  known  as  the  (1)  Upper  or  Spi- 
rifer  Bed,  (2)  the  Middle  or  Fish  Bed,  and  (3)  the  Lower  Ore  Bed. 
No.  1  is  full  of  shells  and  is  about  200  feet  below  the  Catskill  red 
sandstones,  and  at  Mansfield  is  two  to  three  feet  thick.     No.  2  is 
oolitic,  resembles  the  Clinton  ore,  and  affords  fish  remains.     It  lies 
about  200  feet  befow  No.  1  and  varies  up  to  six  or  seven  feet  thick. 
No.  3  is  100  to  200  feet  lower,  and  contains  small  quartz  pebbles.3 
The  ore  is  not  rich,  and  but  little  has  been  mined.     It  is  a  brown- 
ish red  hematite.4 

2.02.11.  Beds  of  red  hematite  are  reported  by  Schmidt  in  the 
Lower  Carboniferous  of  western  central  Missouri.5 

1  A.  F.  Foerste,  "Clinton  Group  Fossils,  with  Special  Reference  to 
Collections  from  Indiana,  Tennessee,  and  Georgia,"  Amer.  Jour.  Sci.,  iii., 
XL.  252.  (Abstract;  original  not  cited.)  "Clinton  Oolitic  I  on  Ores,"  Amer. 
Jour.  Sci,,  iii.,  XLI.  28.    Rec.     "  Notes  on  Clinton  Group  Fossils,  with  Spe- 
cial Reference  to  Collections  from  Maryland,  Tennessee,  and  Georgia, "Proc. 
Post.  Soc.  Nat.  Hist.,  XXIV.  263.     J.  P.  Lesley,   Iron  Manufacturers' 
Guide,  p.  611.  J.S.Newberry,  "Genesis  of  the  Ores  of  Iron,"  School  of  Alines 
Quarterly,  November,  1880,  p.  13.     Rec.     H.  D.  Rogers,   Geol.  of  Penn., 
Vol.  n.,  p.  127.    N.  S.  Shaler,  Geol.  o/Jfy.,  Vol.  III.,  p.  163.     C.  H.  Smyth, 
Jr.,  "  On  the  Clinton  Iron  Ore,"  Amer.  Jour.  Sci.,  June,  1892,  p.  487.    Rec. 

2  W.  N.  Page,  "The  Glenmore  Iron  Estate,  Greenbrier  County,  West 
Virginia,"  M.  E.,  XVII.  115. 

3  A.  S.  McCreath,  Rep.  MM,  Second  Penn.  Survey,  p.  231. 

4  J.  P.  Lesley,  Geol.  of  Penn.,  1888,  Vol.  I.,  p.  311.    A.  Sherwood,  Rep. 
G,  Second  Penn.  Survey,  pp.  33,  37,  41,  42,  67.     A.  S.  McCreath,  Rep.  MM, 
Second  Penn.  Survey,  p.  251. 

5  A.  Schmidt,  "  Iron  Ores  and  Coal  Fields,"  Missouri  Geol.  Survey, 
1872,  p.  169. 


THE  IRON  SERIES,   CONTINUED.  99 

2.02.12.  Example  7.     Crawford  County,  Missouri.     Bodies  of 
specular  and  hard  and  soft  red  hematite,  associated  with  clay  and 
chert,    and    filling    cone-shaped    (base  down)    or  rude   cylindrical 
depressions  in  the  Second  Sandstone  of  the  Missouri  Cambrian. 
The   hard    and  soft  hematites  have  resulted  from  the  alteration 
of  the  specular.     Clay  and  chert  always  accompany  the  ore,  and 
with  it  fill  the  cavities  in   the  broken  and  faulted  Second  Sand- 
stone.    The  deposits  are  distributed  over  several  counties  in  cen- 
tral Missouri,  of  which  Crawford,  Dent,  and  Phelps  are  the  most 
productive.     The  ore,  etc.,  was  thought  by  A.  Schmidt  of  the  Mis- 
souri Survey  (Rep.   1878,  p.  66)  to  have  either  replaced  the  pre- 
existing rock  or  to  have  been  deposited  in  the  hollows  at  the  then 
existing  surface.     Pumpelly,  however,  regards  the  iron  as  having 
been  derived  from   the  weathering  of    the  overlying   First    and 
Second   Limestones,   to   whose   decay  he  likewise    attributed  the 
clay  and   chert.     The  latter,  it  may  be  remarked,  very  generally 
mantle  southern  and  central  Missouri,  and  it  is  probable  that  the 
rocks  have  not  been  submerged  since  Paleozoic  times.    Much  of  the 
drainage,  it  is  thought,  passed  off  through  subterranean  channels 
forming  caves  in  the  Third  Limestone.    To  the  collapse  of  these  is 
attributed  the  formation   of  the  cavities,  in  which  the  ores  were 
laid  down  with  the  residual  clay,  etc.1    The  region  has  afforded  from 
100,000  to  200,000  tons  of  ore  annually.2 

2.02.13.  Examples.     Jefferson  County,  New  York.     Beds  of 
red  hematite,  with  more  or  less  specular,  lying  beneath  sandstones 
of  the  Potsdam  stage  and  associated  with  serpentine,  crystalline 
limestone,  and  other  sandstone  beds  of  uncertain  relations.     Not 
far  aAvay  the  Laurentian  gneiss  outcrops,   although  nowhere  as- 
sociated with  the  ores.    The  beds  occur  along  a  northeast  belt  from 
Philadelphia,    Jefferson    County,   to    Gouverneur,    St.    Lawrence 
County.    They  range  up  to  30  feet  in  thickness,  and  consist  mostly 
of  red,  earthy  hematite  with  included  masses  of  specular.    Many  in- 
teresting minerals   (siderite,  millerite,  chalcodite,  quartz,  etc.)  are 
found  in  cavities.     Brooks  gives  the  following  geological  section. 
1.  Potsdam  sandstone,   40  feet.     2.  Hematites,   40  feet.     3.  Soft 
schistose,  slaty,  green  magnesian  rock  with  pyrite  and  graphite 
(thought  by  Emmons  to  be  igneous),  90  feet  and  more.  4.  Granular, 

1  R.  Pumpelly,  Tenth  Census,Vo}.  XV.,  p.  12. 

2  W.  M.  Chauvenet,   Tenth  Census,  Vol.  XV.,  p.  403 ;  see  also  Pum- 
pelly's  paper,  p.  12.     A.  Schmidt,  "Iron  Ores  and  Coal  Fields,"  Missouri 
GeoL  Survey,  1874,  p.  124.    F.  L.  Nason,  Idem.,  Vol.  II.,  1892,  p.  116.     Rec. 


100  KEMP'S   ORE  DEPOSITS. 

crystalline  limestone  with  phlogopite  and  graphite.  5.  Sandstone 
like  (1),  15  feet.  6.  Crystalline  limestone  with  beds  and  veins  of 
granite.  E.  Emmons,  in  the  early  New  York  Survey  (Geology 
Second  District),  attributed  an  eruptive  origin  to  these  ore  bodies 
and  to  the  associated  serpentine  and  limestone.  Such  an  origin 
is  controverted  by  Brooks,  who  first  recorded  the  lower  lying  sand- 
stone. The  deposits  need  further  study.1 

2.02.14.  Example   9.     Lake  Superior   Hematites.      Bodies  of 
hematite,  both  red  and  specular,  soft  and  hard,  in  metamorphic 
rocks.     They  vary  widely  in  shape,  although  at  times   quite  per- 
fectly lenticular.      They  are  usually  associated  with  jasper  and 
chert,  and  have  for  a  footwall  a  relatively  impervious  rock  of  some 
sort.    Magnetite  is  at  times  present.    Although  of  varying  physical 
structure  and  associations,  all  the  Lake  Superior  hematites  are  here 
grouped  under  one  general  example,  in  order  to  avoid  unnecessary 
subdivisons,  and  to  emphasize  their  related  characters.     There  are 
five  principal  ore-producing  belts  or  districts,  which  are  also  called 
in  instances  "ranges,"  as  they  follow  ranges  of  low  hills.     They 
are,  in  the  order  of  their  chronological  exploitation,  the  Marquette, 
just  south  of  Lake  Superior,  in  Michigan  ;  the  Menominee,  on  the 
southern  border  of  the  Upper  Peninsula  and  partly  in  Wisconsin  ; 
the  Gogebic  or  Penokee-Gogebic,  on  the  northwestern  border  be- 
tween Michigan  and  Wisconsin  ;  the  Vermilion  Lake,  in  Minnesota, 
northwest  of  Lake  Superior  ;  and  the  Mesabi  (Mesaba),  in  the  same 
general  region  as  the  last. 

2.02.15.  The  geology  of  these  districts  has  been  a  subject  of 
much  controversy,  not  alone  in  the  relations  of  the  separate  areas, 
but  in  the  subdivisions  of  a  single  one.    The  ever-present  difficulty 
of  classifying  and  correlating  metamorphic  rocks  has  here  been 
very  great.     Moreover,  there  are  other  separate  districts,  of  re- 
lated geological  structure,  which  ought  also  to  be  brought  into 
harmony,  and  only  at  a  very  recent  date  has  this  been  even  par- 
tially attained. 

2.02.16.  The  ores  and  their  inclosing  rocks  have  usually  been 
called  Huronian,   as   this   is   the   name   formerly  applied   to  the 

1  T.  B.  Brooks,  "On  Certain  Lower  Silurian  Rocks  in  St.  Lawrence 
County,  New  York,"  Amer.  Jour.  Sci.,  iii.  IV.,  p.  22.  G.  S.  Colby,  Jour. 
U.  S.  Asso.  Charcoal  Iron  Workers,  Vol.  XL,  p.  263.  E.  Emmons,  N.  Y. 
Oeol.  Survey,  Second  District,  p.  93.  T.  S.  Hunt,  "Mineralogy  of  the 
Laurentian  Limestones  of  North  America,"  21st  Ann.  Report  Regents  of 
N.  Y.  State  Univ.,  1871.  p.  88.  J.  C.  Smock,  Bulletin  of  N.  Y.  State  Museum. 


THE  IRON  SERIES,    CONTINUED.  101 

schistose  and  metamorphic  rocks  overlying  what  was  conceived  to 
be  the  basal,  gneissic  Laurentiau.  The  later  and  more  careful 
work  has  essentially  modified  such  grouping.  The  reorganization 
has  been  brought  about  by  the  brothers  N.  H.  and  Alexander  Win- 
chell,  by  R.  D.  Irving,  C.  R.  Van  Hise,  and  the  Canadian  geolo- 
gists, especially  A.  C.  Cawfon,  who  has  worked  in  the  Rainy  Lake 
region.  The  definite  introduction  of  Huronian  in  the  classification 

O 

is  especially  due  to  Logan  (1857).  Previously  Foster  and  Whitney 
had  merely  called  all  the  metamorphic  rocks  concerned  with  the 
iron  ores  in  the  Lake  Superior  regions  "Azoic."  T.  B.  Brooks  in 
the  Marquette  district  distinguished  twenty  members  (1873),  but, 
as  Major  Brooks  frankly  states,  the  classification  was  chiefly  in- 
tended to  aid  explorations  for  ores.  Rominger  made  the  classi- 
fication much  simpler  (1884),  and  many  others  have  since  written 
on  the  subject.1 

2.02.17.  As  now  viewed,  the  Laurentian  is  regarded  as  con- 
sisting of  granites  and  gneisses  and  a  higher  series  of  gneisses  and 
schists.  They  are  grouped  under  the  name  of  "  Fundamental  Com- 
plex" by  Irving  and  Van  Hise  (Cascade  Formation  of  Wads- 
worth,  1892),  but  the  upper  series  is  called  Coutchiching  in  the 
Rainy  Lake  Region  by  Lawson.  The  unconformity  is  an  eruptive 
one.  Above  these,  after  an  unconformity  not  always  clearly 
marked,  comes  the  succession  of  schistose  rocks,  which  are  grouped 
together  under  the  name  Algonkian.  They  consist  of  a  lower 
series,  called  by  various  names  in  the  different  regions,  but  which 
in  the  Marquette,  Menominee,  afcd  Yermilion  Lake  districts  contains 
some  of  the  most  important  mines.  It  is  variously  denominated 
Lower  Huronian,  Lower  Marquette,  Keewatin,  Lower  Vermilion, 
and  Menominee  proper  in  the  different  exposures,  and  probably 
the  great  cherty  limestone  of  the  Penokee-Gogebic  series  is  its 
local  equivalent.  In  the  Marquette  district  Wadsworth  has  re- 
cently divided  it  still  further  into  the  Republic  and  Mesnard  forma- 
tions. The  upper  part  follows  an  unconformity  and  is  called  in  the 
different  regions  Upper  Huronian,  Animikie,  Upper  Yermilion,  L^p- 
per  Marquette,  Western  Menominee,  and  Penokee-Gogebic  proper. 

1  See  M.  E.  Wadsworth,  Notes  on  the  Geology  of  the  Iron  and  Copper 
Districts,  1880 ;  N.  H.  Wmchell,  "  A  Last  Word  with  the  Huronian,'* 
Geol  Soc.  Amer.,  Vol.  II.,  p.  85  ;  C.  R.  Van  Hise,  "An  Attempt  to  Har- 
monize some  apparently  conflicting  Views  of  Lake  Superior  Strati- 
graphy," Amer.  Jour.  Sci.,  ii.,  XLI.  117  ;  and  Tenth  Ann.  Rep.  Director 
U.  S.  Geol.  Survey.  The  papers  give  many  references. 


102  KEMP'S   ORE  DEPOSITS. 

For  the  Marquette  region  this  has  also  been  further  divided  by 
Wadsworth  into  two,  the  Holyoke  and  the  Negaunee  formations. 
It  is  much  less  metamorphosed  than  the  lower  member,  and  in  the 
Marquette  district  contains  some  ore.  In  the  Menominee  region 
of  Wisconsin  it  affords  the  deposits  there  wrought  and  carries  the 
ore  in  the  Gogebic  range.  Still  higher,  after  another  unconformity 
follows  the  Keweenawan  (Keweenian)  or  Nipigon.  This  closes 
the  Algonkian.  Still  above  is  the  Potsdam  sandstone. 

2.02.18.  Example  9a.     Marquette  District.      The   Marquette 
district  was  earliest  known  and  has  been  most  thoroughly  studied  ; 
but  owing  to  the  confused  geological  structure,  there  has  been,  as 
already  remarked,  much  discordance  of  interpretation.    In  the  Mar- 
quette district  the  Huronian  Algonkian  rocks  form  a  broad  syn- 
clinal trough  with  many  subordinate  folds  and  several  tongues  or 
projections  running  out  from  the  main  body.    They  rest  on  and  are 
bounded  by  Laurentian    gneiss.      They   consist  of  green  schists, 
quartzites,  banded  jaspers,  slates,  ore  bodies,  and  dikes  altered  to 
"soapstone"  or  "  soaprock."      Brooks  divided  them  into  twenty 
members,  of  which  Beds  VI.,  X.,  XIII.,  and  a  horizon  below  Y. 
afford  the  ore.    Bed  XIII.  contains  the  magnetite,  which  increases 
in  amount  toward  the  western  portion  of  the  field.     Rominger  in 
Vol.  IV.  of  the  Michigan  Survey,  1884,  reduced  the  number  to 
seven.     Irving  and  Van  Hise  have  contributed  much  in  late  years 
toward  a  solution  of  the  geology.     Irving  regarded  the  series  as 
separable  into  a  lower  division  of  greenstone  schists  and  more 
acidic  rocks,  both  of  which  are  dynamically  metamorphosed  erup- 
tive rocks,  and  an  unconformable,  overlying,  iron-bearing  division 
of  sedimentary  origin.     (See  papers  cited  below.)    Van  Hise,  how- 
ever, in  his  latest  paper  places  the  break  above  the  most  important 
ore  bodies. 

2.02.19.  The  ores  were  classed  by  Brooks  under  five  heads — (a) 
Red  specular,  (b)  Magnetic,  (c)  Mixed,  (d)  Soft  Hematites,  and  (e) 
Flag  ores  ;    and  the  grouping  illustrates  very  well  their  general 
characters.  Class  (a)  includes  the  slaty  hematites  that  break  into  ir- 
regular tapering  plates,  and  the  massive  so-called  granular  ores. 
Class  (b)  includes  granular  and  more  or  less  friable  magnetites, 
which  are  related  to  those  described  under  Example  13.     Class  (c) 
includes  the  highly  siliceous  ores,  consisting  of  hematite,  closely 
interlaminated  with  red  or  white  jasper.     When  containing  over 
50$  iron  they  are  at  present   valuable,  but  the  advance  in  con- 
centration, especially  magnetic,  promises  to  make  the  low-grade 


FIG.   17. — Open  cut  in  the  Republic  mine,  Marquette  range,  shoiving  a 
horse  of  jasper.     From  a  photograph  by  H.  A.  Wheeler. 


104  KEMPS  ORE  DEPOSITS. 

ores  available.  Class  (d)  embraces  limonites  closely  related  to 
those  of  Example  2«,  where  they  are  referred  to.  Class  (e)  has  a 
flaggy  structure  and  its  ores  are  related  to  Class  (c),  but  are  less 
distinctly  banded  and  are  mere  local  varieties  of  ferruginous  schists. 

2.02.20.  The  ore  bodies  have  been  in  earlier  years  generally 
regarded  as  true  beds  of  greater  or  less  extent  and  often  of  great 
irregularity.    They  approximate  a  lenticular  shape  in  the  simplest 
development,  as  is  better  shown  in  the  other  less  disturbed  districts. 
In  the  Marquette  region  this  is  at  times  obscured  by  the  excessive 
disturbances.    They  often  follow  the  foldings  of  the  walls,  partic- 
ularly in  synclinal  troughs.      Later  developments  have    brought 
out  the  fact  that  the  ore  bodies  are  associated  with  some  underly- 
ing rock  that  is  relatively  impervious.    The  favorite  one  is  the  so- 
called    soaprock,    an    altered  igneous  intrusion  that   is  chiefly  in 
dikes.     Beds  of  jasper  seem  to  play  the  same  role.     Van  Hise,  in 
his  paper  of  February,  1892,  notes  four  varieties — (1)  Deposits  on 
the  contact  of  a  quartzite  conglomerate  (the  base  of  the  Upper 
Marquette)    and  the  ore-bearing  formation  ;    (2)  deposits  resting 
upon  soaprock,   which  grades  into   massive  diorite  ;   (3)   deposits 
resting  upon  dikes  of  soaprock,  which  follow   along  or  cut  across 
the  ore-bearing  formations  ;  (4)  deposits  interbedded  in  the  jasper 
or  chert.     In  Figure  18  a  generalized  section  taken  from  Van  Hise 
exhibits  these  different  varieties.     On  the  east  the  soft  hematites 
(limonites)  are  first  met  ;  then  in  going  west  the  red  and  specular 
hematites  ;  and  then  the  magnetic  character  increases,  until  at  the 
western   end  of  the  district  the  magnetites  are    most   abundant. 
South  of  the  Marquette  region  and  between  it  and  the  Menominee 
is  found  the  Felch  Mountain  area.    It  consists  of  three  small  basins 
now  cut  off  by  erosion  from  the  main  exposures,  with  which  it  was 
doubtless  at  one  time  connected. 

2.02.21.  The  origin  of  these  ore  bodies  has  been   a  subject   of 
much  controversy.      Detailed  descriptions  of  the  various  hypoth- 
eses will  be  found  in   Wads  worth's  monograph.1      Only  the  im- 
portant  attempts   at  explanation   are  instanced  here.     The  early 
survey  of  Foster  and  Whitney  (1851)  attributed  an  eruptive  origin? 
and  the  same  difficult  thesis  has  since  been  attempted  by  Wads- 
worth  (1880),  who  bases  his  argument  chiefly  on  the  analogy  of 
the  banded  jaspers  to  laminated  felsites,  and  to  the  fact  that  they 
and  the  ore  curve  around  masses  of  inclosing  schist  or  break  across 

1  M.  E.  Wads  worth,  "  Notes  on  the  Iron  and  Copper  Districts  of  Lake 
Superior,"  Ball.      Mus.  Comp.  ZooL,  Vol.  VII.,  No.  1,  July,  1880. 


THE  IRON  SERIES,    CONTINUED. 


105 


them,  like  intruded  dikes.  Wadsworth  mentions  Dr.  Selwyn  of 
the  Canadian  Survey,  and  the  late  C.  E.  Wright,  as  supporters  of 
this  view.  While  it  may  not  as  yet  be  possible  to  demonstrate 
beyond  question  the  true  origin,  it  is  quite  inconceivable  that 


FIG.  18. — Cross  sections  to  illustrate  the  occurrence  and  associations  of 

iron  ore  in  the  Marquette  district,  Michigan.     After  C.  R.  Van  Hixe, 

Amer.  Jour.  Sci.,  February,  1892;  Engineering  and  Mining 

Journal,  July  9, 1892. 

a  nearly  pure  siliceous  rock  and  an  equally  pure  basic  oxide  should 
be  side  by  side  and  intimately  associated  as  intrusive  masses.  They 
would  combine.  Quite  large  masses  of  iron  oxide  may  and  do  oc- 
cur as  segregations  of  basic  magmas  ;  not,  however,  in  any  amount 
in  acidic.  All  other  geologists  who  have  given  the  matter  atten- 
tion concur  in  some  form  of  sedimentary  origin,  or  in  origin  by  re- 

$ 

TY 


106  KEMPS   ORE  DEPOSITS. 

placement.  The  beds  thus  formed  may  have  been  afterward 
metamorphosed.  Credner,  Brooks,  Wright  in  his  published  work, 
and  at  first  Irving,  described  them  as  having  formed  as  beds  of 
limonite.  These  were  conceived  to  have  been  metamorphosed  in 
the  general  metamorphism  of  the  region.  Brooks  thought  it  pos- 
sible that  the  hematites  were  altered  magnetites,  an  idea  confirmed 
by  the  presence  of  martite,  but  he  considered  all  to  have  been 
limonite  originally.  Irving's  views  are  set  forth  under  Example  9c. 
Yan  Hise's  latest  work  traces  much  the  same  relations  as  in  the 
less  disturbed  Gogebic  district.  He  emphasizes  the  almost  in- 
variable occurrence  of  the  ore  along  the  contact  of  chert  and  in- 
trusive dikes,  which  are  now  altered  to  so-called  soapstone.  This 
relation  is  shown  in  Fig.  18.  The  ores  are  thought  to  have  re- 
placed these  walls,  synclinal  troughs  having  been  favorite  points 
of  deposition.  E.  Reyer  considered  that  the  iron  had  been  leached 
from  the  neighboring,  basic  eruptive  rocks  (green  schists),  and  had 
'been  precipitated  as  hydrate.  The  eruptives  are,  in  this  view, 
regarded  as  submarine,  and  the  similar  association  of  basic  erup- 
tives with*the  iron  ores  of  Elba  is  commented  on. 

2.02.22.  It  was  in  the  forties  that  the  importance  and  extent  of 
the  ore  bodies  were  first  vaguely  suspected.  The  trouble  that  they 
made  with  the  compasses  of  the  early  land  surveyors  indicated 
their  existence.  Important  mining  began  in  1854.  Somewhat 
over  100,000  tons  were  produced  in  1860,  over  800,000  in  1870, 
nearly  1,500,000  in  1880.  In  1877  the  Menominee  region  was 
opened,  and  in  1885  the  Penokee-Gogebic  and  Vermilion  districts 
began  to  ship.  The  total  shipments  from  the  Lake  Superior  region 
in  1890  were  8,982,531  tons.  The  total  production  to  1891  of  the 
Marquette  district  was  32,700,000  tons.  A  quite  complete  citation 
of  the  literature  is  to  be  found  in  Wads  worth's  monograph,  already 
referred  to,  and  in  Irving's  "  Copper-bearing  Rocks  of  Lake 
Superior,"  Monograph  No.  V.,  II.  8.  Geol.  Survey.  See  also  under 
Examples  95,  9c,  and  9d.  Only  the  most  important  or  most  recent 
papers  are  mentioned  here.1 

1  J.  Birkinbine,  "Resources  of  the  Lake  Superior  District,''  M.  E., 
July,  1887.  T.  B.  Brooks,  Geol.  Survey  of  Michigan,  Vol.  I.,  1873;  Geol. 
Survey  of  Wisconsin,  Vol.  III.,  p.  450.  H.  Credner.  "  Die  vorsilurischen 
Gebilde  df>r  oberen  Halbinsol  von  Michigan  in  Nord  Amerika,"  Zeitsch.  d. 
d.  Geol.  Ges.,  1889,  XXL  516;  also  Berg.-  und  Huett.  Zeit.,  1871,  p.  369. 
Foster  and  Whitney,  Geol.  of  the  Lake  Superior  District,  Vol.  L,  "Iron 
Lands,"  1851.  R.  D.  Irving,  "O  i  the  Origin  of  the  Ferruginous  Schists  and 


THE  IRON  SERIES,    CONTINUED.  107 

2.02.23.  Example  9&.  Menominee  District.  The  Menominee 
River,  which  gives  the  district  its  name,  forms  the  southeasterly 
boundary  between  the  Upper  Peninsula  of  Michigan  and  Wiscon- 
sin. The  mines  are  situated  about  forty  miles  south  of  the  Mar- 
quette  group,  and  the  same  distance  west  of  Lake  Michigan.  The 
larger  number  are  in  Michigan,  but  the  productive  belt  extends 
also  into  Wisconsin.  They  lie  along  the  south  side  of  an  east  and 
west  range  of  hills,  which  rise  from  200  to  300  feet  above  the 
surrounding  swampy  land.  The  geological  section  immediately 
associated  with  the  ore  involves  the  following,  all  of  which  corre- 
sponds to  the  Lower  Marquette  as  outlined  in  the  introduction.  The 
cherty  limestone  is  local.  (1)  Norway  limestone  (named  from  the 
Norway  mine),  a  belt  of  siliceous  limestone,  1200  feet  thick;  (2) 
Quinnesec  ore  group,  consisting  of  limestone,  siliceous  or  jaspery 
slates,  black  and  flesh-colored,  hydromica  schists  and  slates  and  ore 
beds,  1000  feet  ;  (3)  Lake  Hanbury  slate  group,  slates  and  schists 
with  quartzose  bands.  Unconformably  on  these  lies  the  hori- 
zontal Potsdam  sandstone.  The  ore  occurs  along  two  or  three 

Iron  Ores  of  the  Lake  Superior  Region,"  Amer.  Jour.  Sci.,  iii.,  XXXII.  263; 
''Preliminary  Paper  on  an  Investigation  of  the  Archaean  of  the  North- 
western States,"  Fifth  Ann.  Rep.  Director  U.  S.  Geol.  Survey,  p.  131 ; 
Seventh  Ann.  Rep.,  p.  431 ;  also,  Administrative  Reports,  in  subsequent 
volumes.  J.  P.  Kimball,  "  The  Iron  Ore  of  the  Marquette  District,"  Amer. 
Jour.  Sci. ,  ii. ,  XXXIX.  290.  H.  S.  Munroe,  School  of  Mines  Quarterly,  III. , 
p.  43.  E.  Reyer,  "Geologic  der  Amerikanischen  Eisenerzlagerstatten 
(insbesondere  Michigan),"  Oest.  Zeit.  f.  Berg.-  u.  Hutt.,  Vol.  XXXV.,  pp. 
120,  131,  1887.  C.  Rominger,  Geol.  Survey  of  Michigan,  Vol.  IV.,  1884. 
C.  R.  Van  Hise,  "  An  Attempt  to  Harmonize  Some  Apparently  Conflicting1 
Views  of  Lake  Superior  Stratigraphy,"  Amer.  Jour.  Sci.,  iii.,  XLL.  p.  117, 
February,  1891;  Tenth  Ann.  Rep.  Director  U.  S.  Geol.  Survey  ;  "The  Iron 
Ores  of  the  Marquette  District  of  Michigan,"  Amer.  Jour.  Sci.,  February, 
1892,  p.  115.  M.  E.  Wadsworth,  "Notes  on  the  Iron  and  Copper  Districts 
of  Lake  Superior,"  Bull.  Mus.  Comp.  Zool,  VII.  1, 1880  ;  "On  the  Origin 
of  the  Iron  Ores  of  the  Marquette  District,  Lake  Superior,"  Proc.  Bost. 
Soc.  Nat.  Hist.,  Vol.  XX.,  p.  470 ;  Engineering  and  Mining  Journal,  Oct. 
29,  1881,  p.  286  ;  Ann.  Rep.  Mich.  State  Geologist,  1891-92.  "The  Geology 
of  the  Lake  Superior  Region,"  in  a  pamphlet  issued  by  the  Duluth,  South 
Shore  and  Atlantic  R.  R.,  1892.  Dr.  Wadsworth  announces  a  new  subdi- 
vision of  Formations  in  this  and  in  Amer.  Jour.  Sci.,  January,  1893,  p.  73. 
H.  Wedding,  Zeitsch.  f.  Berg.-,  Hutt.-,  und  Salinenwesen  in  Preus.  Staat., 
XXIV.,  p.  339.  C.  E.  Wright  and  C.  D.  Lawton,  Reps,  of  the  Commis- 
sioners of  Mineral  Statistics  of  Michigan,  1880,  and  annually  to  date. 
G.  H.  Williams,  "  Greenstone  Schist  Areas  cf  the  Menominee  and  Mar- 
quette Regions  of  Michigan,"  introduction  by  R.  D.  Irving,  Bull.  G2,U.  S. 
Geol.  Survey. 


108 


KEMP'S    ORE  DEPOSITS. 


planes  of  deposition  in  (2)  and  not  far  from  the  contact  with  (1), 
while  minor  bodies  have  been  found  in  the  Potsdam,  which  seem 
to  have  resulted  by  the  erosion  of  the  older  lenses  in  the  Potsdam 
times.  (See  paper  by  J.  Fulton,  cited  below.)  Especially  instruc- 
tive exposures  of  green  schists  are  found  which  have  furnished 
some  of  the  best  evidence  that  they  are  metamorphosed,  igneous,  in- 
trusive rocks.  The  ores  are  generally  soft,  blue,  earthy  hematites, 
which  give  a  red  powder  and  consist  of  very  finely  divided  parti- 
cles of  specular.  The  brown  hematites  are  of  very  limited  occur- 
rence, being  known  only  in  the  Emmet  mine.  The  lenticular  shape 
of  the  ore  bodies  is  better  shown  than  in  the  Marquette  district,  and 
even  the  large  masses  clearly  exhibit  this  cross  section.  They  strike 
about  N.  75°  W.,  and  dip  70°  to  80°  N.  They  also  pitch  to  the 


FKJ.  19. — plan  of  Ludington  ore  body,  Menominee  district,  Michigan. 
After  P.  Larsson,  M.  E.,  July,  1887. 

west;  i.e.,  run  down  diagonally  on  the  dip.  (Cf.  New  Jersey  Mag- 
netite, Example  13d).  There  were  produced  up  to  1891  a  grand 
total  of  12,800,000  tons  since  mining  began.1 

2.02.24.  Example  9c.  Penokee-Gogebic  District.  This  lies  in 
an  east  and  west  range  of  hills,  which  crosses  the  westerly  boun- 
dary of  the  Upper  Peninsula  and  Wisconsin,  and  is  from  ten  to 
twenty  miles  south  of  Lake  Superior,  and  eighty  to  one  hundred 

1  T.  B.  Brooks,  Geol.  Survey  of  Wisconsin,  Vol.  III.,  430-663.  D.  H. 
Brown,  "Distribution  of  Phosphorus  in  the  Ludington  Mine,"  M.  E., 
XVI.  525.  J.  Fulton,  "Mode  of  Deposition  of  the  Iron  Ores  of  the  Me- 
nominee Range,  Michigan,"  M.  E.,  XVI.  525.  Per.  Larsson,  "The 
Chapin  Mine,"  M.  E.,  XVI.  119.  C.  E.  Wright,  Geol.  Survey  of  Wiscon- 
sin, III.  666,  734.  G.  H.  Williams,  "  Greenstone-Schist  Areas  of  the  Me- 
nominee and  Marquette  Regions  of  Michigan,  with  an  Introduction  by  R. 
D.  Irving,"  Bull  62,  U.  S.  Geol.  Survey. 


THE  IRON  SERIES,    CONTINUED. 


109 


miles  west  of  the  Marquette  mines.  The  rocks  are  less  metamor- 
phosed than  in  the  previous  two  districts.  The  strata  run  east  and 
west  with  a  northerly  dip  of  60°  to  80°,  and  with  no  subordinate 
folds.  They  consist  of  cherty  limestone  at  the  base,  followed  by 
quartz,  slates,  quartzite,  iron  ore,  and  ferruginous  cherts,  and  final- 
ly slate  and  schists.  The  strata  are  traversed  by  dikes.  The  ore 
is  a  soft,  red,  somewhat  hydrated  hematite,  with  more  or  less  man- 
ganese, which  is  often  considerable  and  is  most  abundant  in  the 
southern  mines.  Hard  specular  is  rare.  Irving  first  showed  that  these 
ore  bodies  had  originated  from  the  replacement  of  dolomitic  or 


FIG.  20. — Cross  section  of  the  Colby  mine,  Penokee- Gogebic  district,  Mich- 
igan, to  illustrate  occurrence  and  origin  of  the  ore.    After  C.  R. 
Van  Hise,  Amer.  Jour.  Sci.,  January,  1891. 

calcitic  beds  with  iron  oxide.  Since  then  Van  Hise  has  proved 
them  to  be  in  the  troughs  formed  by  the  intersection  of  northerly 
dipping  compact  quartzites  and  southerly  dipping  trap  dikes.  .  He 
has  traced  the  iron  to  a  source  in  the  layers  of  cherty  carbonates, 
parallel  with  the  quartzites  and  above  them.  From  this  it  has 
been  leached  out  by  the  percolating  water  and  has  been  deposited 
in  the  apices  of  the  troughs,  where  it  has  replaced  the  original  car- 
bonate rocks'.  Somewhat  the  same  process  is  outlined  for  the  Mar- 
quette ores  in  his  latest  paper.  Up  to  1891,  there  were  produced 
a  grand  total  of  8,300,000  tones  of  ore.1 

1  R.  D.  Irving,  Geol.  Survey  of  Wisconsin,  III.,  pp.  100-167, 1880.   "  Or- 
igin of  the  Ferruginous  Schists  and  Iron  Ores  of  the  Lake  Superior  Re- 


110  KEMP'S    ORE  DEPOSITS. 

2.02.25.  Example  9d,  Vermilion  Lake,  Minnesota.  Beds  of 
hard  specular  with  but  little  soft,  intimately  associated  with  jas- 
per (or  jaspilyte,  as  locally  called),  and  both  contained  in  green 
schists.  The  district  is  situated  in  the  northeastern  corner  of 
Minnesota,  and  northwest  of  Lake  Superior.  Two  Harbors,  the 
shipping  point,  is  twenty-six  miles  east  of  Duluth.  and  Tower, 
the  chief  mining  town,  is  sixty-seven  miles  from  the  docks.  Leav- 
ing the  lake,  the  railroad  first  crosses  the  north  flank  of  the  Lake 
Superior  synclinal,  consisting  of  southerly  dipping  igneous  rocks 
belonging  to  the  Keweenawan.  Underlying  these  are  a  series  of 
gabbros  and  augite-syenites  that  contain  titaniferous  magnetite 
and  may  be  a  parallel  to  the  Adirondack  norites.  Next  follow  the 
black  slates  of  the  Animikie,  and  then  a  heavy  quartzite  called  the 
Pewabic  quartzite.  N.  H.  Winchell  applies  to  these  collectively 
the  name  Taconic,  a  term  which  the  best  work  in  the  East  rejects 
in  its  home.  They  form  the  Mesabi  range  of  hills.  Sedimentary, 
gneissic,  and  eruptive  exposures,  referred  to  the  Laurentian,  suc- 
ceed in  the  north.  Next  come  the  Vermilion  mica  and  hornblende 
schistc,  and  after  these  the  Keewatin  sericitic  schists,  jaspilyte, 
etc.,  containing  the  ore  bodies  at  Tower.  The  Laurentian  rocks 
appear  again  on  the  north,  arid  beyond  to  the  northwest  is  the 
Rainy  Lake  region,  studied  by  A.  C.  Lawson.  All  the  formations 
referred  to  above  run  in  belts,  having  a  general  direction  north  and 
east.  The  ore  bodies  which  are  important  as  yet  are  all  in  the 
Keewatin.  They  vary  in  size  from  small  bodies  up  to  masses, 
which  extend  as  much  as  a  mile  on  the  strike.  They  approximate 
the  lenticular  shape  so  characteristic  of  crystalline  iron  ore  de- 
posits. The  jasper,  or  jaspilyte,  is  everywhere  associated,  often 
very  intimately,  in  parallel  bands  with  the  ore,  while  the  contain- 
ing rock  is  a  green  schist  which  is  regarded  as  an  altered  igneous 
rock  or  tuff.  The  principal  mines  are  located  at  Tower,  on  Ver- 
milion Lake,  and  at  Ely,  which  is  twenty-three  miles  farther  north- 
east. N.  H.  and  H.  V.  Winchell,  in  the  Bulletin  referred  to  be- 


gion,"  Amer.  Jour.  Sci.,  iii.,  XXXII.  263,  265;  see  also  under  Van 
C.  D.  Lawton,  "Go^ebic  Iron  Mines,''  Engineering  and  Mining  Journal, 
Jan.  15,  1887,  p.  42.  C.  R.  Van  Hise,  "On  the  Origin  of  the  Mica 
Schists  and  Black  Mica  Slates  of  the  Penokee-Gogebic  Iron  bearing  Se- 
ries," Amer.  Jour.  Sci,,  iii.,  XXXI.  453-459.  "The  Iron  Ores  of  the 
Penokee-Gogebic  Series  in  Michigan  and  Wisconsin,"  Amer.  Jour.  Sci., 
iii.,  XXXVII.  32.  C.  E.  Wright,  Geol.  Survey  of  Wisconsin,  III.,  pp.  239- 
301. 


THE  IRON  SERIES,    CONTINUED.  Ill 

low,  draw  a  parallel  between  the  more  crystalline  rocks  and  the 
Vermilion  schists  on  the  one  hand,  and  the  more  sericitic  and 
hydrated  rocks  of  the  Keewatin  on  the  other.  The  latter  consist 
chiefly  of  a  chloritic  mineral,  a  sericitic  mineral,  a  feldspathxc  min- 
eral, mostly  plagioclase,  and  of  hematite.  The  former  exhibit  a 
hornblendic  mineral,  a  micaceous  mineral,  a  feldspathic  mineral, 
mostly  orthoclase,  and  magnetite.  A  passage  of  one  series  of 
rocks  into  the  other  is  not  at  all  an  inconceivable  metamorphic 
process.  These  last  mentioned  magnetites  are  not  as  yet  produc- 
tive, although  regarded  as  promising.  There  are  titaniferous 
magnetites  in  the  gabbros  and  also  other  undeveloped  hematites 
in  the  Animikie.  Still  other  magnetites  occur  in  the  Pewabic 
quartzite,  recently  shown  to  be  of  value.  The  ores  from  Tower 
and  Ely  are  high-grade  Bessemer,  and  are  produced  in  great  quan- 
tity. Nearly  400,000  tons  of  all  kinds  were  shipped  in  1887  and 
891,910  in  1890,  making  a  grand  total  of  3,200,000. 

2.02.26.  N.  H.  and  H.  Y.  Winchell  have  argued  that  these 
ores  originated  as  marine  chemical  precipitates.    The  great  extent  of 
igneous  rocks  associated  with  them  leads  to  the  suggestion  that  the 
inclosing  rocks  have  been  formed  by  submarine  volcanoes,  whose 
lapilli,  etc.,  have  largely  contributed  their  materials.     Deposits  of 
iron  and  silica  are  thought  to  have  formed  from  the  heated  over- 
lying waters.     Somewhat  similar  views  of  the  extensive  ore  bodies 
of  Elba  are  held  abroad.1 

The  general  geological  relations  are  also  discussed  in  many  of 
the  papers  cited  under  the  other  districts,  especially  those  of  Irving 
and  Van  Hise. 

2.02.27.  Example  9e.     Mesabi  Range.    Of  much  more  recent 
development    than    the    other   districts   is   the   Mesabi   range    of 
Minnesota.     The  mines  are  not  yet  shipping  ore  (1892),  but  prom- 
ise to  in  1893.     The  indications  are  that  the  deposits  are  not  less 
extensive  than  in  any  other  of  the  Lake  Superior  localities,  if  in- 

1  A.  H.  Chester,  Eleventh  Ann.  Rep.  Minn.  Oeol.  Survey,  155,  167. 
T.  B.  Comstock,  "Vermilion  Lake  District  in  British  America,"  M.  E., 
July,  1887.  H.  V.  Winchell,  "  The  Diabasic  Schists  containing  the  Jaspilyte 
Beds  of  Northeastern  Minnesota,"  Amer.  Geol.,  II.  18.  N.  H.  and  H.  V. 
Winchell,  "  On  a  Possible  Chemical  Origin  of  the  Iron  Ores  of  the  Keewatin 
in  Minnesota,"  Amer.  Oeol.,  IV.  291,  389;  "The  Taconic  Iron  Ores  of 
Minnesota  and  of  Western  New  England,"  Amer.  GeoL,  VI.  263;  "The 
Iron  Ores  of  Minnesota,"  Bull.  VI. ,  Minn.  Geol.  Survey.  Rec.  Ann.  Re- 
ports of  the  Minn.  Geol.  Survey. 


««  '.TTf 


112 


KEMPS   ORE  DEPOSITS. 


deed  they  are  not  even  larger  and  of  a  form  to  be  more  easily 
mined.  The  present  developments  are  situated  southwest  of  Ver- 
milion Lake,  and  nearer  Duluth  and  Lake  Superior.  The  ore  lies 
under  the  black  slates  called  Animikie  in  the  section  given  in 
Paragraph  2.02.25,  and  over  the  quartzite,  there  called  the  Pewa- 
bic  ;  but  they  are  situated  twenty  miles  or  so  west  of  the  line  of 
that  section.  The  ore  bodies  are  all  south  of  the  granite  ridge 
called  the  Giants'  range.  Upon  the  southern  slopes  of  this  range 
lie  the  green  schists  of  the  Keewatin,  which  are  unconformably 
overlain  by  the  Pewabic  quartzite.  On  this  rests  the  ore-bearing 


FIG.  21. — General  cross  section  of  ore  body  at  Biwabik,  Mesabi  Range, 
Minn.    After  H.  V.  Winchell,  2Qth  Ann.  Rep.  Minn.  State  Geologist. 

rock,  which  is  a  jaspery  quartzite,  called  taconyte  by  H.  V.  Win- 
chell.  Over  this,  in  order,  come  greenish  siliceous  slates  and 
cherts,  black  slates  (referred  to  the  Animikie),  and  great  masses  of 
gabbro.  On  the  flanks  of  the  Giants'  range  the  dip  is  steep,  but 
it  flattens  out  nearly  to  horizontality  away  from  the  granite.  All 
the  formations  above  the  Keewatin  are  called  Taconic  by  the  Win- 
chells. 

2.02.28.  The  ore  bodies  lie  on  the  southerly  slopes  of  low  hills, 
and  are  found  immediately  below  the  mantle  of  glacial  drift,  which 
varies  up  to  100  feet  in  thickness.  Ore  indications  have  long  been 
known  on  the  range,  and  various  reports  have  been  made  in  previ- 
ous years,  although  always  unfavorably.  The  indications  ^ 


THE  IRON  SERIES,    CONTINUED.  113 

available  showed  only  siliceous  limonites  of  low  grade.  Deep 
test  pits,  which  penetrated  these  caps  and  the  drift,  have,  how- 
ever, rewarded  persistent  prospecting.  The  ore  is  both  soft, 
blue,  earthy,  and  sandy  hematite,  and  hard  specular.  With  these 
are  limonites  and  paint  ores.  The  sections  show  at  times  fifty 
feet  and  more  of  excellent  hematite,  which  may  be  of  excep- 
tional purity  and  far  below  the  Bessemer  limit  of  phosphorus,  or 
which  may  slightly  exceed  it,  but  in  general  the  published  analyses 
would  show  them  to  be  quite  high-grade,  siliceous,  low  phosphorus 
ores. 

The  ore  bodies  lie  in  the  jaspery  quartzite  (taconyte)  along  its 
outcrop.  They  may  be  directly  on  the  Pewabic  quartzite,  as- 
seems  usual,  or  else  entirely  in  the  taconyte.  They  fade  out  into 
the  latter  along  the  dip.  They  are  regarded  by  H.  V.  Winchell,, 
to  whose  description  the  above  is  chiefly  due,  as  having  originated 
by  replacement  of  the  taconyte.  This  rock  sometimes  contains 
calcareous  streaks,  which  have  perhaps  aided  in  furnishing  the 
carbonic  acid,  which,  it  is  thought,  has  dissolved  the  silica  of  the 
quartzite  (taconyte)  in  the  replacement  process.  The  greater  part 
of  it,  however,  has  doubtless  been  atmospheric,  and  has  by  its 
solvent  action  concentrated  the  iron  already  disseminated  in  the 
taconyte.  Mesabi  is  also  written  Mesaba  and  Missabe.1 

2.02.29.  Example  10.    James  River,  Virginia.    Specular  hema- 
tite in  narrow  beds  (lenses),  interstratified  with  quartzites  and  slates 
of  metamorphic  character  and  Archaean  age.     They  run  four  to  six 
feet,  or  less,  in  thickness,  with  prevailingly  vertical  dip,  but  they 
also  pitch  diagonally  down  on  the  dip  like  the  lenses  of  magnetite,, 

'later  described.  They  furnish  a  very  excellent  grade  of  ore.  The 
ore  bodies  are  found  along  both  sides  of  the  James  River,  a  few 
miles  above  Lynchburg.  Some  magnetite  also  occurs  in  the  region, 
and  some  limonite.  More  or  less  clay  accompanies  the  ore.2 

2.02.30.  Similar  lenses  of  specular  ore  and  magnetite  are  found 

1  H.  V.  Winchell,  Twentieth  Ann.  Rep.  Minn.  State  Geologist,  p.  112,. 
1892  ;  reprinted  M.  E.,  1892.     Rec.     The  New  York  Times  of  Dec.  14,  1892,, 
has  a  quite  extended  account.     H.  V.  Winchell  and  J.  T.  Jones,  "The  Bi- 
wabik  Mine,"  M.  E.,  February,  1893. 

2  E.  B.  Benton,  Tenth  Census,  Vol.  XV.,  p.  263  (on  Virginia).     J.  L.. 
Campbell,  Geology  and  Resources  of  the  James  River  Valley,  p.  49,  New 
York,  1882.     B.  Willis,  Tenth  Census,  Vol.  XV,  p.  301.     The  Virginias,  a 
monthly  formerly  published  by  Jed.  Hotchkiss,  at  Staunton,  contains  much 
information  on  Virginia  in  general. 


114 


KEMP'S   ORE  DEPOSITS. 


£ 


in  central  North  Carolina,  in  schistose 
rocks,  which  have  been  referred  to  the 
Huronian. 

2.02.31.  Lenses    of    specular  hem- 
atite of  very  excellent  quality  are  found 
also  in  metamorphic  rocks,  north  of  Fort 
Laramie,  Wyoming,  which  may  prove 
productive  in  time.     But  little  is  as  yet 
known  about  them. 

2.02.32.  Example  11.     Pilot  Knob, 
Mo.     Two  beds  of  hard  specular  hem- 
atite separated  by  a  thin  seam  of  so- 
called  slate  (probably  volcanic  tuff),  and 
interstratified  with  breccias  and  sheets 
of  porphyry.     Along  the  eastern  limit 
of   the    Ozark   uplift  of    Missouri  and 
Arkansas  a  series  of  knobs  of  granite 
and  porphyritic  rocks  project  through 
the    Cambrian    limestones    and    sand- 
stones.    They  are  older  than  the  lime- 
stones, and   clearly   were  not  intruded 
through    them.     The    limestones    and 
sandstones  lie  up  against  the  porphyry 
and  in  the  valleys  between.     The  un- 
derlying porphyry  has  been   found  in 
the  valley  near  Pilot  Knob,  after  pene- 
trating four  hundred  feet  of  sediment- 
ary  rocks.       The    porphyry    and    ores 
have  often  been  called  Huronian,  but 
in  view  of  the  recent  reorganization  of 
the  Huronian  (see  Example  9),  this  is 
not  done,  nor  ever  has  been,  on  any  ac- 
curate grounds.     Pilot  Knob  is  formed 
by  one  of  these  eruptive  knobs.     It  con- 
sists of  sheets  of  porphyries  that  are 
capped  by  porphyry  breccia,   the  two 
ore  beds,  and  the  intervening  tuff.     The 
beds  strike  and  dip  13°  S.  S.  ^^r.     The 
hill  is  over  600  feet  high.     The  lower 
bed  has  furnished  most  of  the  ore,  run- 
ning from  25  to  40  feet  thick,  and  af- 
fording a  dense  bluish,  specular  hema- 
tite of  from  50  to  60#  Fe,  siliceous,  and 
very  low  in  phosphorus.     The  upper  bed 


THE  IRON  SERIES,    CONTINUED. 


115 


is  irregular  and  of  lower  grade  and  runs  from  6  to  10  feet  thick. 
The  Pilot  Knob  mines  in  this  solid  ore  are  now  substantially 
exhausted. 

Recent  drill  holes  ou  the  northerly  slope  and  below  the  out- 
cropping face  of  ore  have  shown  that  under  the  Cambrian  strata  of 


FIG.  23.—  View  of  open  cut  at  Pilot  Knob,  Mo.,  shoiving  the  bedded  char- 
acter of  the  iron  ore.    From  a  photograph  by  J.  F.  Kemp,  1888. 

the  valley  there  is  a  great  bed  of  ore  boulders  or  breccia  in  clay, 
much  as  is  the  case  at  Iron  Mountain,  later  described.  Analyses 
of  cores  were  not,  however,  sufficiently  encouraging  for  develop- 
ment during  the  present  low  prices  for  iron.  Doubtless  the  bed 
will  afford  important  reserves. 

2.02.33.     Near   Pilot  Knob  are   two  other  hills  of  porphyry, 


116 


KEMP'S  ORE  DEPOSITS. 


Shepherd  Mountain  and 
Cedar  Mountain,  whose 
ores  are  structurally  more 
related  to  Example  11  a. 
The  first  contains  three 
veins,  the  Champion,  the 
North,  and  the  South.  They 
are  long  and  narrow  (4  to 
10  feet),  strike  north  60° 
to  70°  east,  and  dip  70° 
north.  The  Champion  vein 
contained  a  little  streak  of 
natural  lodestone,  but  the 
ore  is  mostly  specular. 

The  North  vein  shows 
a  good  breast  of  ore  five 
feet  wide,  but  too  full  of 
pyrite  to  be  available.  Ce- 
dar Mountain  has  a  vein  of 
specular  ore.  Neither  hill 
has  been  an  important  pro- 
ducer. Minor  veins  have 
been  found  on  neighboring 
porphyry  hills  (Buf  ord,  Ho- 
gan,  and  Lewis  mountains), 
some  of  which  contain 
much  manganese. 

2.02.34.  Example  11«. 
Iron  Mountain,  Missouri. 
Veins  of  hard,  specular 
hematite  irregularly  seam- 
ing a  knob  of  porphyry. 
Iron  Mountain  is  five  or 
six  miles  north  of  Pilot 
Knob,  and  is  a  low  hill  with 
a  westerly  spur  called  Lit- 
tle Mountain,  and  has  also 
a  northerly  spur.  It  con- 
sists of  feldspar  porphyries, 
more  or  less  altered.  These 


THE  IRON  SERIES,   CONTINUED. 


117 


are  seamed  with  one  large,  and  on  the 
west  somewhat  dome-shaped,  parent 
mass  of  ore,  and  innumerable  minor 
veins  that  radiate  into  the  surrounding 
rock.  Upon  the  flanks  of  the  porphyry 
hill  rests  a  mantling  succession  of  sedi- 
mentary rocks,  that  dip  away  on  a]l 
sides.  The  lowest  member  is  a  con- 
glomerate of  ore  fragments,  weathered 
porphyry,  and  residual  clay  left  by  its 
alteration.  It  is  regarded  by  Pumpelly 
as  formed  by  pre-Silurian  surface  dis- 
integration and  not  by  shore  action, 
inasmuch  as  sand  does  not  fill  the  in- 
terstices, while  white  porphyry  clay 
does.  It  is,  however,  overlain  by  a  thin 
bed  of  coarse,  friable  sandstone,  which 
marks  the  advance  of  the  sea,  and  whose 
formation  preceded  the  limestones. 
This  conglomerate  is  now  the  principal 
source  of  the  ore.  It  is  mined  under- 
ground, hoisted  and  washed  by  hy- 
draulic methods,  like  those  employed 
in  the  auriferous  gravels  of  California, 
and  then  jigged.  The  apatite  has  largely 
weathered  out  of  it.  The  rock  of  the 
mountain  itself,  in  the  cuts  of  the  mines, 
is  largely  kaolinized,  and  exhibits  every- 
where the  effects  of  extreme  alteration. 
The  smaller  veins  that  penetrate  the 
porphyry  show  at  times  casts  or  much 
altered  cores  of  apatite  crystals. 

2.02.35.  The  porphyries  of  Pilot 
Knob  and  Iron  Mountain,  in  thin  sec- 
tion, are  seen  to  belong  to  quartz-por- 
phyries, feldspar-porphyries,  and  por- 
phy rites.  Both  orthoclase  and  plagio- 
clase  are  present  in  them,  and  many 
interesting  forms  of  structure.  One 
significant  fact  is  that  they  are  every- 
where filled  with  dusty  particles  of  iron 
oxide,  probably  magnetite.  Our  knowl- 


118 


KEMP'S   ORE  DEPOSITS. 


edge  of  the  chemical  composition  of  the  porphyries  is,  however,  as 
yet  very  imperfect.  An  eruptive  origin  was  originally  assigned  to 
these  ores  by  J.  D.  Whitney  (Metallic  Wealth  of  the  United  States, 
p.  479,  1854),  just  as  to  the  Lake  Superior  hematites.  The  later 
investigations  of  Adolph  Schmidt  for  the  Missouri  Survey  in  1871 
arrived  at  a  different  conclusion.  Dr.  Schmidt  considered  them, 
whether  occurring  in  an  apparent  bed,  as  at  Pilot  Knob,  or  in 
various  more  or  less  irregular  veins,  as  at  Iron  Mountain,  to  have 
been  formed  either  by  a  replacement  of  the  porphyries  with  iron 
oxide  deposited  from  solution,  or  by  a  filling  in  the  same  way  of 
fissures,  probably  formed  by  the  contraction  of  the  porphyry  in 
cooling.  In  the  valuable  report  on  iron  ores  by  F.  L.  Nason  in 
the  Missouri  Geological  Survey  a  sedimentary  origin  is  advo- 
cated for  the  Pilot  Knob  beds.  They  are  conceived  to  have  been 
deposited  in  a  body  of  water  in  a  hollow,  between  formerly  exist- 
ing porphyry  hills,  which  rose  above.  In  the  course  of  weathering, 
the  hills  became  the  valleys  and  the  early  sedimentary  beds  the  hill- 
top. It  is,  however,  somewhat  difficult  to  understand  how  the  more 
or  less  incoherent  sediments  withstood  degradation  better  than  the 
hard,  firm  porphyry  hills.  Some  such  origin  as  sedimentation  or  re- 
placement is,  however,  the  only  reasonable  one.  It  is  not  improbable 
that  the  Pilot  Knob  ores  originated  in  the  saturation  and  more  or  less 
complete  replacement  of  tuf  aceous  layers  with  infiltrating  iron  oxide. 
An  extended  table  of  analyses  of  Iron  Mountain  ores  will  be 
found  in  Mineral  Resources  of  the  United  States,  1889-90,  p.  47.1 

ANALYSES    OP    HEMATITES,    BED    AND    SPECULAR. 

(The  same  discrimination  must  be  employed  in  looking  over  these 
analyses  that  was  emphasized  under  limonite.) 


Fe. 

P. 

S. 

s,os. 

A1803 

H2O. 

Clinton  N  Y  (fossil  ore). 

44  10 

0  6">0 

0  23 

12.63 

5.45 

2.77 

Wisconsin  (fossil  ore)  

51.75 

1.392 

Pennsylvania  (Mifflin  ore)  

44.4 

0.115 

0.028 

Tennessee  (Meigs  County)  

51.63 

0.345 

56.4 

0.34 

16.8 

0.5 

46.32 

0.883 

Missouri  (Crawford  County)  

Marquette  dist.,  Mich,  (specular). 
«<              «          «<             « 

Menominee  district,  Michigan.  . 
Iron  Mountain,  Mo     

59.41 
68.4 
64.83 
60.47 
65.5 

0.085 
0.53 
0.067 
.009 
0.040 

0.010 

207 
3.60 
3.38 
5.75 

2.03 

Pilot  Knob,  Mo  

59.15 

0.015 

13.27 

2.19 

James  River  (Maud  vein)  
Elba  

49.89 
61.81 

0.139 
0.02 

0.17 

5.97 

3.47 

70.0 

1  G.  C.  Broadhead,  "The  Geological  History  of  the  Ozark  Uplift," 


THE  IRON  SERIES,    CONTINUED.  119 

These  analyses  are  mostly  taken  from  State  reports  and  from 
Mineral  Resources  of  the  United  States.  They  are  intended  to 
illustrate  the  general  run  of  compositions,  but  for  Birmingham  and 
Marquette  are  high.  Analyses  vary  widely. 

Amer.  GeoL,  III.  6.  J.  R.  Gage,  "  On  the  Occurrence  of  Iron  Ores  in  Mis- 
souri," Trans.  St.  Louis  Acad.  Sci.,  1873,  Vol.  III.,  p.  181.  E.  Harrison, 
"  Age  of  the  Porphyry  Hills,"  Ibid.,  Vol.  II.,  p.  504.  E.  Haworth,  "  A  Con- 
tribution to  the  Archaean  Geology  of  Missouri,"  Amer.  GeoL,  I.  280-363  ; 
"Age  and  Origin  of  the  Crystalline  Rocks  of  Missouri,  "Bull.  F.,  Mo.  Oeol. 
Survey,  1891.  A.  V.  Leonhard,  "Notes  on  the  Mineralogy  of  Missouri," 
Trans.  St.  Louis  Acad.  Sci.,  Vol.  IV.,  p.  440.  F.  L.  Nasoa,  "Report  on 
the  Iron  Ores  of  Missouii,''  Mo.  GeoL  Survey,  II.  Rec.  R.  Pumpelly, 
"  Geology  of  Pilot  Knob  and  Vicinity,"  Mo.  GeoL  Survey,  1872,  p.  5  ;  see 
also  remarks  on  Iron  Mountain,  Bull.  GeoL  Soc.  Amer.,  Vol.  II.,  p.  220. 
Rec.  W.  B.  Potter,  "  The  Iron  Ore  Regions  of  Missouri,"  Journal  U.  S. 
Asso.  Charcoal  Iron  Workers,  Vol.  VI.,  p.  23.  Rec.  F.  A.  Sampson,  "A 
Bibliography  of  the  Geology  of  Missouri,"  Bull.  II.,  Mo.  GeoL  Survey,  1890. 
(This  is  a  valuable  book  of  reference.)  F.  Shepherd,  Ann.  Rep.  Mo.  GeoL 
Survey,  1853-54.  Hist.  A.  Schmidt,  "  Iron  Ores  of  Missouri,"  Mo.  GeoL 
Survey ,  1872,  p.  45,  and  especially  p.  94.  Rec.  J.  D.  Whitney,  Metallic 
Wealth  of  the  U.  S.,  p.  479 


CHAPTER   III. 

MAGNETITE  AND  PYRITE. 

2.03.01.  Example  12.     Magnetite  Beds.     Beds  of  magnetite, 
often  of  lenticular  shape,  interstratified  with  Archaean  gneisses  and 
crystalline  limestones.       They  are   extensively  developed  in  the 
Adirondacks,  in  the  New  York  and  New  Jersey  Highlands,  and  in 
western  North  Carolina.     The  presence  of  magnetite  in  Michigan 
(Example  9a),  in  Minnesota  (Example  6#),  on  Shepherd   Mountain 
in   Missouri   (Example   11),    and    in   Virginia    (Example   12)     has 
already  been  referred  to.     Other  magnetite  bodies  are  known  in 
Colorado,  Utah,  California,  and  Wyoming,  and  will  be  mentioned 
subsequently.     Titanium  is  often  present  in  such  amounts   as   to 
render  the  ore  of  no  value.     The  same  is  true  of  pyrite  and  pyrrho- 
tite.     Apatite  is  always  found,  although  it  may  be  in  very  small 
quantity.     Chlorite,  hornblende,  augite,  epidote,  quartz,  feldspar, 
and  a  little  calcite  are  the  common  associated  minerals.     In  New 
Jersey  the  beds  occur  in  several  parallel  ranges  or  belts. 

2.03.02.  Example  I2a.     Adirondack  Region.     The  magnetite 
deposits  occur  in  the  foothills  of  the  Adirondacks  on   all   sides, 
and  to  a  less  extent  in  the  mountains  themselves.     The  mountains 
are  very  largely  knobs  of  a  rock,  which  is  chiefly  labradorite,  with 
some  hypersthene  and  other  bisilicates,  and  is  variously  called  lab- 
rador-rock,    norite,    hypersthene-rock,    anorthosite,    etc.     Whether 
this  is  igneous  or  a  series  of  metamorphosed  sediments,  it  is  not  yet 
generally  admitted,  as  the  geology  of  the  region  largely  remains  to 
be  worked  out.     It  certainly  exhibits  both  metamorphic  and  igne- 
ous facies  and  is  undoubtedly  a  more  or  less  metamorphosed  igne- 
ous rock.     Associated  with  it,  especially  in  the  foothills,  are  gneiss 
and  crystalline  limestones,  in  the  former  of  which  occur  the  mag- 
netite deposits    now  wrought,   but  field  work  in  the  summer  of 
1892  has  convinced  the  writer  that  there  are  large  bodies  of  magne- 
tite in  true  igneous  gabbros  in  the  town  of  Westport,  if  not  else- 
where.   At  Lyon  Mountain,  on  the  north,  the  Chateaugay  ore  body 


MAGNETITE  AND  PYRITE. 


121 


is  really  a  bed  of  gneiss  very  rich  in  magnetite,  rich  enough  in 
places  to  afford  a  merchantable  ore.  The  greater  part  of  it,  how- 
ever, requires  concentration.  It  is  known  for  several  miles  on  the 
outcrop.  On  either  side  the  ore  shades  out  into  the  walls  of  bar- 
ren rock.  The  Little  River  mines  on  the  west  side,  in  St.  Law- 


FIG.  26. — View  of  open  cut  and  underground  work  in  Mine  21,  Mineville, 
near  Port  Henry,  N.  Y.    Photographed  by  J.  F,  Kemp,  1892. 

rence  County,  appear  to  be  a  similar  but  larger  bed  or  group  of 
beds  of  lean  ore,  said  to  be  from  800  to  J500  feet  wide  and  t\vo 
miles  long.  The  Barton  Hill  mines,  near  Mineville,  are  openings  on 
a  single  connected  zone  and  extend,  together  with  Fisher  Hill,  over 
a  mile  on  the  strike. 

2.03.03.     Besides  these  extended  beds  there  are  otner  deposits 


122  KEMP'S   ORE  DEPOSITS. 

exhibiting  more  perfectly  the  peculiar  lenticular  shape  characteris- 
tic of  magnetite,  and  to  this  class  are  to  be  referred  the  greater 
number  of  smaller  bodies  (Hammondville).  They  pinch  and  swell, 
roll  and  fold  and  feather  out,  and  often  come  off  sharply  from  the 
walls.  They  frequently  follow  and  overlap  one  another  like  shin- 
gles, the  second  one  succeeding  the  first  in  the  footwall.  They  are 
not  infrequently  cut  by  trap  dikes  and  are  thrown  by  these  and  by 
normal  faults.  At  Hammondville  small  gulches  seem  to  cut  off 
the  ore,  and  are  probably  due  to  faults.  Other  deposits  are  of 
enormous  size,  as  at  Mineville  (200  to  300  feet  clear  ore  between 
the  walls),  and  their  relations  are  less  clear.  They  may  be  large 
lenses  doubled  over  in  a  sigmoidfold.  The  Champlain  magnetite  is 
quite  notably  granular  as  contrasted  with  New  Jersey,  which  tend& 
rather  more  to  break  in  prisms. 

2.03.04.  C.  E.  Hall  has  divided  the  metamorphic  rocks  of  the 
Adirondacks  into  the  (a)  Lower  Laurentian  Magnetite  Iron  Ore 
series,  containing  the  most  important  ore  beds,  (b)  The  Lauren- 
tian Sulphur  Ore  Series,  (c)  The  Limestones  and  the  Labrador  or 
Upper  Laurentian,  with  Titaniferous  Iron  Ores,  (c)  is  thought  to 
be  certainly  later  than  (a),  but  the  relations  of  (b)  are  uncertain. 
T.  S.  Hunt  also  states  that  the  titaniferous  ores  are  associated  with 
the  Labradorite  series  or  Norian,  which  he  places  as  of  later  age 
than  the  gneisses  with  the  good  ore. 

Commercially  the  ores  are  divided  into  (1)  ores  high  in  phos- 
phorus but  low  in  sulphur  ;  (2)  ores  low  in  both  phosphorus  and 
sulphur;  (3)  pyritous  ores;  (4)  titaniferous  ores  (Tenth  Census, 
Vol.  XV.).  Under  class  (4)  come  numerous  beds  which  are  worth- 
less, but  which  if  the  titanium  could  be  neutralized  would  be  very 
valuable  (Lake  Henderson  ;  see  Addenda.).  Mineville  is  by  far 
the  most  productive  region.  It  ships  400,000  to  500,000  tons  yearly. 
Chateaugay  and  Hammondville  are  next.  The  Arnold  mines  pro- 
duce some,  while  the  Palmer  Hill  mines  with  the  decline  of  the 
bloomaries  have  gradually  ceased.  The  mines  on  the  west  side  of 
the  mountains  are  less  important.  They  afford,  so  far  as  developed, 
a  low  grade  of  ore,  that,  however,  with  the  improvements  in  mag- 
netic concentration,  seems  to  promise  well.  The  largest  openings 
are  at  Jayville  and  Little  River. 

There  are  numerous  magnetite  deposits  in  Canada  of  analogous 
geological  relations,  but  they  are  often  highly  titaniferous.1 

1  L.  C.  Beck,  Mineralogy  of  New  York,  Part  I.,  pp.  1-38.     J.  Birkin- 


MAGNETITE  AND  PYRITE.  123 

2.03.05.  Example  I2b.  New  York  and  New  Jersey  Highlands, 
and  the  South  Mountain  of  Pennsylvania.  Beds  of  lenticular  shape 
in  Archaean  gneiss  and  crystalline  limestone.  From  Putnam  County, 
New  York,  a  ridge  of  Archaean  rocks  runs  southwest  across  the 
Hudson  River,  traversing  Orange  County,  New  York,  and  northern 
New  Jersey,  and  running  out  in  Pennsylvania.  Lenses  of  magne- 
tite occur  throughout  its  entire  extent.  They  are  not  as  large  as 
in  the  Adirondacks,  but  are  more  regularly  distributed.  East  of 
the  Hudson,  in  Putnam  County,  the  Tilly  Foster  mine  is  the  most 
important,  and  the  descriptions  and  figures  of  it  are  the  best  illus- 
trations of  the  shape  of  lenses  published.  West  of  the  Hudson,  in 
Orange  County,  the  Forest  of  Dean  mine  affords  considerable  ore 
yearly.  It  is  cut  by  an  interesting  trap  dike.  As  the  results  of 
study  of  the  Archaean  of  this  region,  N.  L.  Britton  has  divided  it 
into  a  Lower  Massive  group,  a  Middle  Iron  Bearing,  and  an  Upper 
Schistose.  (Geol  of  N.  J.,  1886,  p.  77.)  F.  L.  Nason  has  also 
sought  to  classify  it  on  the  basis  of  rock  types,  of  which  he  makes 
four,  named,  from  their  typical  occurrences,  Mount  Hope  type, 
Oxford  type,  Franklin  type,  and  Montville  type.  They  are  ar- 


bine,  "  Crystalline  Magnetite  in  the  Port  Henry  (N  Y. )  Mines,"  M.  E.,  Feb- 
ruary, 1890.  Rec.  H.  Credner,  Zeitsch.  d.  d.  g.  Gesell. ,  1869,  XXI.,  p.  516; 
B.  und  H.  Zeit.,  1871,  369.  J.  D.  Dana,  "On  the  Theories  of  Origin," 
Amer.  Jour.  Sci.,  in.,  XXII.  152,  402.  E.  Emmons,  Geology  of  New  York, 
Second  District,  pp.  87,  98,  231,  255,  291,  309,  350.  Hist.  C.  E.  Hall, 
"Laurentian  Magnetite  Ore  Deposits  of  Northern  New  York,"  32d  Ann. 
Rep.  State  Museum,  1884,  p.  133.  Rec.  J.  F.  Kemp,  "  Notes  on  the  Miner- 
als Occurring  near  Port  Henry,  N.  Y.,"  Amer.  Jour.  Sci.,  iii.,  XI.  62,  and 
Zeitsch.  f.  Kryst.,  XIX.  183.  G.  W.  Maynard,  "The  Iron  Ores  of  Lake 
Champlain,"  Brit.  Iron  and  Steel  Inst.,  Vol.  I  ,  1874.  W.  C.  Redfield, 
"Some  Account  of  Two  Visits  to  the  Mountains  of  Essex  County,  N.  Y., 
in  1836-37,"  Amer.  Jour.  Sci.,  i.,  XXXIII.  301.  Hist.  B.  Silliman,  "Re- 
marks on  the  Magnetites  of  Clifton,  St.  Lawrence  County,  N.  Y.,"  M.  E., 
I.  364.  J.  C.  Smock,  "Iron  Mines  of  New  York,"  Bull.  VII.,  N.  Y.  State 
Museum.  Rec.  J.  Stewart,  "Laurentian  Low  Grade  Phosphate  Ores," 
M.  E.,  February,  1892.  Wedding,  Zeitschr.  /.  B.,  H.,  und  S.  im.  p.  St., 
XXIV.  330,  1876.  See  also  the  general  works  on  Iron  Ores  cited  at  begin- 
ning of  Part  II.  On  Canadian  magnetites  the  following  papers  may  be 
mentioned.  F.  P.  Dewey,  "Some  Canadian  Iron  Ores,"  M.  E.,  XII.  192. 
B.  J.  Harrington,  "  On  the  Iron  Ores  of  Canada,"  Can.  Geol.  Survey,  1873- 
74.  T.  S.  Hunt,  Can.  Geol.  Survey,  1866-69,  pp.  261,  262.  T.  D.  Ledyard, 
"  Some  Ontario  Magnetites,"  M.  E.,  XIX.  28,  and  July,  1891.  W.  H.  Mer- 
ritt,  "  Occurrence  of  Magnetite  Ore  Deposits  in  Victoria  County,  Ontario," 
A.  A.  A.  S.t  XXXI.  413,  1882. 


124  KEMP'S   ORE  DEPOSITS. 

ranged  in  their  orcler  of  probable  age.  They  correspond  in  some 
respects  to  Britton's  grouping,  but  differ  materially  in  others. 
(G-eol  of  N.  J.,  .1889,  p.  30.)  Four  courses,  or  mine-belts,  have 
been  recognized  in  New  Jersey, — the  Rarnapo,  the  Passaic,  the  Mus- 
conetcong,  and  the  Pequest, — in  order  from  east  to  west.  The 
lenses  strike  northeast  with  the  gneisses,  and  usually  have,  like 
them,  high  dips.  In  addition  they  have  also  a  so-called  "  pitch  " 


FIG.  27a.  FlG. 

FIGS.  27a  and  276.— Model  of  the  Tilly  Foster  ore  body.    27a,  Top  view, 

showing  faulted  shoulder.     After  F.  S.  Ruttmann,  Trans.  Amer. 

Inst.  Min.  Eng.,  XV.  79.     276,  View  of  bottom  of  same. 

Photographed  by  J.  F.  Kemp  from  the  model  now 

at  the  School  of  Mines,  Columbia  College. 

along  the  strike,  so  that  they  run  diagonally  down  the  dip.  They 
have  been  observed  to  pitch  northeast  with  an  easterly  dip  and 
southwest  with  a  westerly.  Either  by  the  overlapping  of  lenses 
or  by  an  approximation  to  an  elongated  bed,  they  sometimes,  as  at 
Hibernia,  extend  a  mile  or  more  in  unbroken  series.  Again,  they 
may  be  almost  circular  in  cross  section  (Hurd  mine).  At  Frank- 
lin Furnace  one  is  found  in  crystalline  limestone.1 

1  E.  S.  Breidenbaugh,  "On  the  Minerals  Found  at  the  Tilly  Foster 
Mine,  New  York,"  Amer.  Jour.  ScL,  iii.,  VI.  207.    J.  F.  Kemp,  "  Diorite 


MAGNETITE  AND  PYRITE.  125 

2.03.06.  South  Mountain,  Penn.     Small  lenses  of  magnetite  oc- 
cur in  Berks,  Bucks,  and  Lehigh  counties  of  southeastern  Pennsyl- 
vania, in  the  metamorphic  rocks  of  the  South  Mountain  belt.  They 
are  very  like  those  to  the  north  in   New  Jersey,  but  are  lower  in 
both  iron  and  phosphorus.     Their  product  is  about  100,000   tons 
yearly.      The  Cornwall  magnetite  is  described  under  Example  13, 
for  its  geological  structure  is  entirely  different  from  the  lenses.1 

2.03.07.  Example  12c.     Western  North  Carolina  and  Virginia. 
Beds  of  magnetite,  of  the  characters  already  described,  in  Archaean 
gneisses  and  schists.     The  ore  body  at  Cranberry,  N.  C.,  is  the  lar- 
gest and  best  known.     It  occurs  in  Mitchell  County,  and  has  lately 
been  connected  by  rail  with  the  lines  in  east  Tennessee.     Accord- 
ing to  Kerr,  the  principal  outcrop  is  1500  feet  long  and  200  to  800 
feet  broad  ;  but,  of  course,  all  of  this  is  not  ore.     The  mines  can 
afford  very  large  quantities  of  excellent  Bessemer  grade.     Pyrox- 
ene and  epidote  are  associated  with  the  ore.    Kerr  has  referred  the 
magnetite  to  the  Upper  Laurentian.     In  the  southern  central  por- 
tions of  North  Carolina  other  magnetites  occur  in  the  mica  and  tal- 
cose  schists,  which  have  been  referred  to  the  Huronian.     Specular 
hematite  is  associated  with  them.     (Example  10.)     Magnetite  has 
also  been  lately  reported  from  Franklin  and  Henry  counties,  Virginia, 
and  Stokes  County,  North  Carolina,  which  may  be  available  in  the 
future.     Some  doubt,  however,  is  cast  on  its  amount  and  quality.2 

Dike  at  the  Forest  of  Dean  Mine,"  Amer.  Jour.  Sci.,  iii.,  XXXV.  331. 
F.  H.  McDowell,  "  The  Reopening  of  the  Tilly  Foster  Mine,"  M.  E.,  XVII. 
758  ;  Engineering  and  Mining  Journal,  Sept.  7, 1889,  206.  F.  S.  Ruttman, 
"  Notes  on  the  Geology  of  the  Tilly  Foster  Ore  Body,  Putnam  County, 
New  York,"  M.  E.,  XV.  79.  Rec.  J.  C.  Smock,  Bull.  VII.,  N.  Y.  State 
Museum.  Rec.  A.  F.  Wendt,  "  The  Iron  Mines  of  Putnam  County,"  M.  E., 
XIII.  478.  "Iron  Mines  of  New  Jersey,"  School  of  Mines  Quarterly,  iv., 
III.  N.  L.  Britton,  Ann.  Rep.  N.  J.  Survey,  1886,  p.  77.  Rec.  G.  H. 
Cook  and  J.  C.  Smock,  Geol.  of  N.  J.,  1868.  Rec.  (See  also  subsequent 
annual  reports,  especially  1873,  p.  12.)  F.  L.  Nason,  Ann.  Rep.  N.  J. 
Survey,  1889.  Rec.  J.  W.  Pullmann,  "The  Production  of  the  Hibernia 
Mine,  New  Jersey,"  M.  E.,  XIV.  904.  J.  C.  Smock,  "The  Magnetite  Iron 
Ores  of  New  Jersey,"  M.  E.,  II.  314 ;  "  A  Review  of  the  Iron  Mining  In- 
dustry of  New  Jersey,"  M.  E.,  June,  1891.  Rec. 

1  E.  D'Invilliers,  Rep.  D3,  Penn.  Survey,  Vol.  II.  (South  Mountain 
Belt  of  Berks  County).    Rec.     F.  Prime,  Rep.  D3,  Vol.  I.  Penn.  Survey 
(Lehigh  County).     B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p.  179. 

2  W.  C.  Kerr,  Geol.  of  N.  C.,  1875,  264.    H.  B.  C.  Nitze,  "  On  Some  of 
the  Magnetites  of  Southwestern  Virginia,  etc.,  and  Discussion  of  Same, 
by  E.  C.  Pechin,"  M.  E.,  June,  1891.     B.  Willis,  Tenth  Census,  Vol.  XV., 
p.  325.     Engineering  and  Mining  Journal,  Jan.  7,  1888. 


126  KEMP'S  ORE  DEPOSITS. 

2.03.08.  Example  I2cl     Colorado  Magnetites.     Beds  of  mag- 
netite of  a  lenticular  character  in  rocks  described  as  syenite  (Chaf- 
fee  County)  and  diorite  (Fremont  County).  With  these  a  number  of 
others  are  mentioned  which  vary  from  the  example,  but  of  which 
more  information  is  needed  before  they  can  be  well  classified.    The 
last  are  mere  prospects.    The  mines  in  Chaffee  County  have  been  the 
only  actual  producers.     There  are  three  principal  claims — the  Cal- 
umet, Hecla,  and  Smithfield.     They  extend  continuously  over  4000 
feet.     The  wall  rock  is  called  syenite.     Chauvenet  describes  them 
as  having  resulted  from  the  oxidation  of  pyrites,  and  as  being  in 
rocks  of  Silurian  age.     They  average  57$  Fe,  with  only  0.009  P, 
but  are  comparatively  high  in  S,  reaching  0.1  to  2.0&     These  mines 
and  those  at  the  Hot  Springs,  mentioned  under  Example  2,  have 
furnished  the  Pueblo  furnaces  with  most  of  their  stock.     The  de- 
posit in  Fremont  County  is  at  Iron  Mountain,  but  is  too  titanifer- 
ous  to  be  valuable.     It  is  a  lenticular  mass  in  so-called  diorite.     A 
large  ore  body  has  been  reported  from  Costillo  County,  in  limestone 
(Census  Report)  or  syenite  (Rolker).     In  Gunnison  County,  at  the 
Iron  King  and  Cumberland  mines,  excellent  ore  occurs  in  quartz- 
ites  and  limestones,  called  Silurian.     At  Ashcroft,    near  Aspen, 
high  up  on  the  northern  side  of  the  Elk  Mountains,  is  a  great  bed 
or  vein  of  magnetite,  in    limestones  of  Carboniferous    age,   with 
abundant  eruptive  rocks  near.    It  is  thought  by  Devereux  to  be  al- 
tered pyrite.     Still,  pyrite  is  a  common  thing  with  magnetite  else- 
where.    There  are  other  smaller  deposits  in  Boulder  County  and 
elsewhere  in  the  State.1 

2.03.09.  In  Wyoming  an  immense  mass  of  titaniferous  magne- 
tite is  known  near  Chugwater  Creek.     It  is  described  by  Hague  as 
resembling  a  great  dike  in  granite.2     Gabbro  is  in  the  neighborhood. 

2.03.10.  Example  I2e.     California  Magnetite.     Beds  of  mag- 
netite of  lenticular  shape  in  metamorphic  slates  and  limestones  on 
the  western  slope  of  the  Sierra  Nevada.     Others  of  different  char- 
acter are  also  known.      In   Sierra  and  Placer  counties  lenses    of 
excellent  ore  are  found,  accompanying  an  extended  stratum  of  lime- 

1  R.  Chauvenet,  "  Papers  on  Iron  Prospects  of  Colorado,"  Ann.  Heps. 
Colo.  State  School  of  Mines,  1885  and  1887 ;  also  M.  E.,  Denver  meeting, 
1889.    Rec.    W.  B.  Devereux,  "  Notes  on  Iron  Prospects  in  Pitkin  County, 
Colorado,"  M.  E.,  XII.  608.      B.  T.  Putnam,  Tenth  Census,  Vol.  XV.,  p. 
472.    Rec.    C.  M.  Rolker,   "  Notes  on  Iron  Ore  Deposits  in  Colorado," 
M.  E.,  XIV.  266.    Rec. 

2  "  Iron  Mountain,  Wyoming,"  4Qth  Parallel  Survey,  Vol.  II.,  p.  14. 


MAGNETITE  AND  PYRITE.  127 

stone  in  chlorite  slate.  A  great  ore  body  of  magnetite  described 
as  a  vein  has  lately  been  reported  from  San  Bernardino  County. 
It  is  said  to  be  from  30  to  150  feet  thick,  and  to  lie  between  dolo- 
mitic  limestone  and  syenite.1  A  great  bed  of  a  kind  not  specified 
is  reported  from  San  Diego  County.2 

2.03.11.  Example  13.  Cornwall,  Penn.  Immense  beds  of 
soft  magnetite,  associated  with  green  slates,  limestones  of  Cambrian 
age,  and  Triassic  sandstones.  They  are  pierced  by  dikes  of  Trias- 
sic  diabase.  The  exact  geological  relations  of  these  beds  have 
been  greatly  disputed,  the  doubtful  point  being  whether  they  are  of 
Triassic  or  Siluro-Cambrian  age.  They  occur  just  at  the  juncture. 
of  schists  of  the  latter  with  red  sandstones  of  the  former.  The 
most  probable  explanation  is  that  they  were  originally  an  immense 
deposit  of  Siluro-Cambrian  limonite  (Example  2a),  which  has  been 
changed  to  magnetite  by  the  diabase  eruptions.  They  have  been 


LIMESTONEj 

CORNWALL  MINE 

H     SECTION  ON  LINE  A.B.OF  MAP         -t 

|      i  ii  ••  i  -i  350  FT.  - 

FIG.  28.— Cross  section  of  the  magnetite  ore  body  at  Cornwall,  Penn. 
After  Bailey  Willis,  Tenth  Census,  Vol.  XV.,  p.  226. 

thought  eruptive  also,  an  idea  far  less  probable.  The  ore  forms 
two  low  hills.  It  is  mined  by  open  cuts.  The  amount  is  enormous, 
600,000  to  700,000  tons  being  shipped  yearly.  Up  to  1888  more 
than  8,500,000  tons  had  been  mined.  The  ore  is  rather  low  in  iron 
but  is  not  high  in  phosphorus.  Considerable  amounts  of  copper 
ores  (chalcopyrite,  etc.)  occur  in  fissures  crossing  the  magnetite. 
Farther  southwest,  in  York  County,  the  Dillsburg  group  of 
mines  affords  specular  hematite  and  magnetite  from  deposits  in 
Triassic  sandstones.3 


1  Ann.  Rep.  State  Mineralogist,  1889,  p  235. 

2  Ibid.,  1889,  p.  154.    J.  R.  Browne,  "  Mineral  Resources  West  of  the 
Rocky  Mountains,"  1868.    C.  King  and  J.  D.  Hague,  "Mineral  Resources 
West  of  the  Rocky  Mountains,"  1874,  p.  44.    H.  G.  Hanks  and  W.  Irelanr 
Ann.  Reps,  State  Mineralogist,  California.    (Very  little  on  iron.)    F.  von 
Richthofen,  private  reports  quoted  in  Tenth  Census,  Vol.  XV.,  p.  495, 
J.  D.  Whitney,  Geol.  Survey  Gal.,  Vol.  I. 

3  P.  A.  Fraser,  "  Study  of  the  Specular  and  Hematite  Ores  of  Iron  of 
the  New  Red  Sandstone  in  York  County,  Pennsylvania,"  M.  E.,  V.  132. 


128  KEMP'S   ORE  DEPOSITS. 

2.03.12.  Example  14.      Iron  County,    Utah.       Beds  of  mag- 
netite and   hematite  bearing  evidence    of   being  metamorphosed 
limonite,  in  limestones  of  questionable  Silurian  age,  and  associated 
with  eruptive  rocks  described  as  trachyte.     The  limestones  have 
been  much  upturned,  metamorphosed,  and  pierced  by  dikes  and 
eruptive  masses.    The  ore  forms  great  projecting  ridges  and  prom- 
inent outcrops,  locally  called  "  blow-outs."     The  usual  lenticular 
shape  is  not  lacking.     They  occur  over  an  area  of  fifteen  by  five 
miles,  and   are  in  the  southern   end  of   the  Wasatch  Mountains. 
The  samples  show  rich  ores,  which  at  times  exceed  the  Bessemer 
limit  of  phosphorus.     In  the  Star  district  the  ore  apparently  lies 
between  quartzite  and  granite.     Hematite  occurs  in  large  amount, 
as  does  quartz,  while  some  streaks  have  large  crystals  of  apatite. 
The  importance  of  the  deposits  lies  in  the  future.     They  are  the 
largest  in  the  West,  and  are  interesting  in  their  bearing  on  the 
general  origin   of  magnetite.     Coal,   not  proved   to  be  good   for 
smelting,   is  near,  but   centers  of  iron   consumption  are  very  far 
away.1 

2.03.13.  Example  15.     Magnetite  Sands.     Beds  of  magnetite 
sands    concentrated  on  beaches  or  bars   by    waves    and    streams. 
The  magnetite  has  been  derived  from  the  weathering  of  igneous 
and   metamorphic   rocks,    through    which    it   is    everywhere   dis- 
tributed.    When  in  the  sand  of  a  sea  beach,  it  and  other  heavy 
minerals  tend  to  be  concentrated  by  the  sorting  action  of  the  waves. 
They  resist  the  retreating  undertow  better  than  lighter  materials. 
Such  deposits  are  very  abundant  at  Moisie,  on  the  St.  Lawrence, 
below  Quebec,  and  in  the  United  States  are  known  in  smaller  de- 
velopments   on    Lake    Champlain  ;    at    Quogue,   L.    I.;    on   Block 
Island  ;  in  Connecticut ;  along  the  Great  Lakes,  and  on  the  Pacific 
coast.     Grains  of  garnet,  olivine,  hornblende,  etc.,  minerals  of  high 


Also  Penn.  Survey,  Rep.  C2.  E.  V.  D'lavilliers,  "Cornwall  Iron  Ore 
Mines,"  M.  E.,  XIV.  873.  Rec.  Lesley  and  D'lnvilliers,  Ann.  Rep,  Second 
Penn.  Survey,  1885.  J.  P.  Lesley,  Final  Report,  Vol.  I.,  p.  351, 1892.  Rec. 
T.  S.  Hunt,  "The  Cornwall  Mines,"  etc.,  M.  E.,  IV.  319.  H.  D.  Rogers, 
First  Penn.  Geol.  Survey,  II.  718.  B.  Willis,  Tenth  Census,  Vol.  XV.,  p. 
223.  Rec. 

1  W.  P.  Blake,  "Iron  Ore  Deposits  of  Southern  Utah,"  M.  E.,  XIV. 
809.  J.  S.  Newberry,  "  Genesis  of  Our  Iron  Ores,"  School  of  Mines  Quar- 
terly, March,  1880.  Rec.  Engineering  and  Mining  Journal,  April  23, 
1881 ,  p.  286.  Proc.  National  Academy,  1880.  B.  T.  Putnam ,  Tenth  Census, 
Vol.  XV.  486.  Rec. 


MAGNETITE  AND  PYRITE. 

specific  gravity,  are  also  in  the  sands.  Many  are  too  high  in 
titanium  to  be  of  use,  but  there  is  no  more  difficulty  in  concentrat- 
ing them  than  artificially  crushed  ore.  In  Brazil  and  New  Zea- 
land they  have  attracted  attention.1 

2.03.14.  On  the  Origin  of  Magnetite  Deposits. — It  is  important 
to  note  that  magnetite  deposits  are  almost  always  in  metamorphic 
rocks,  which  owe  their  character  to  regional  metamorphism,  or  to 
the  neighborhood  of  igneous  rocks  (Pennsylvania  and  Utah). 
Gneisses  form  the  commonest  walls,  but  so-called  norites,  or  gab- 
bros,  and  crystalline  limestones  also  contain  them.  Where  there 
is  lamination,  or  bedding,  the  magnetite  conforms  to  it.  As  the  his- 
tory of  the  metamorphic  rocks  is  so  often  uncertain,  the  magnetites 
share  the  same  doubt.  In  igneous  rocks  magnetite  is  the  most 
widely  occurring  of  the  rock-making  minerals.  In  all  explanations 
the  prevailing  lenticular  shape,  the  general  arrangement  in  linear 
order,  and  the  existence  of  great  beds  must,  be  considered.  The 
shape  is  very  similar  to  that  of  deposits  of  specular  hematite,  with 
which  magnetite  is  often  associated.  (Examples  9  and  10.)  The 
following  hypotheses  have  been  advanced  as  to  their  origin  :  1.  As 
intruded  (eruptive)  masses.  This  supposes  an  origin  for  the  lenses 
on  the  analogy  of  a  trap  dike.  Though  formerly  much  advocated, 
it  is  now  generally  rejected.  2.  As  excessively  basic  portions  of 
igneous  rocks.  This  supposes  that  large  amounts  of  iron  oxide 
separate  in  the  cooling  and  crystallizing  of  basic  magmas.  There 
are  such  occurrences,  although  seldom,  if  ever,  pure  enough  or 
abundant  enough  for  mining.  The  titaniferous  magnetite  of  the 
Minnesota  gabbros  has  been  alluded  to  (2.02.25),  and  also  the 
Brazilian  ore  and  the  Cumberland  Hill  (R.  I.)  peridotite.  (See 
also  Dakyns  and  Teall,  Q.  J.  G.  &,  XLVIIL,  p.  118.)  Should 
such  igneous  rocks  be  subjected  to  regional  metamorphism  and 
the  stretching  action  characteristic  of  it,  the  ore  masses  might  be 
drawn  out  into  lenses.  3.  As  metamorphosed  limonite  beds.  This 
idea  has  been  most  widely  accepted  in  the  past.  It  presupposes 
limonite  beds  formed  as  in  Examples  1  and  2,  which  become  buried 
and  subjected  to  metamorphism,  changing  the  ore  to  magnetite 
and  the  walls  to  schists  and  gneisses.  Igneous  rocks  have  ap- 
parently changed  limonites  to  magnetite  at  Cornwall,  Penn.,  and 
in  Utah,  but  such  changes  by  regional  metamorphism  are  less  easy 

1  T.  S.  Hunt,  Geol.  Survey  Canada,  1866-69,  261,  262;  Canad.  Nat., 
VI.  79.  A.  A.  Julien,  "  The  Genesis  of  the  Crystalline  Iron  Ores,"  Acad. 
Nat.  Sci.,  Phil.,  1882,  335  ;,  Engineering  and  Mining  Journal,  Feb.  2,  188^ 

-»  '  V 

J?£j£o*»nir 


130  KEMP'S   ORE  DEPOSITS. 

to  demonstrate.  The  limonite  may  Lave  resulted  from  the  oxida- 
tion of  lenses  of  pyrite.  4.  As  replaced  limestone  beds,  or  as  sider- 
ite  beds  subsequently  metamorphosed.  Such  deposits  may  pass 
through  a  limonite  stage.  The  general  process  is  outlined  under 
Example  9c,  as  developed  by  Irving  and  Van  Hise  in  the  Gogebic 
district.  The  lenticular  deposits  of  siderite  at  the  Burden  mines 
(Example  4)  are  very  suggestive,  and  some  such  original  mass 
might  in  instances  be  metamorphosed  to  magnetite.  5.  As  sub- 
marine chemical  precipitates.  This  is  outlined  under  Example  9c?, 
as  applied  by  the-  Winchells  in  Minnesota.  6.  As  beach  sands. 
The  lenses  are  regarded  as  having  been  formed  as  outlined  under 
Example  15.  The  same  heavy  minerals  sometimes  occur  with 
magnetite  lenses  as  are  found  on  beaches.  (See  B.  J.  Harrington, 
Can.  Geol.  Survey,  1873,  193  ;  A.  A.  Julien,  Phil.  Acad.  Sci.y. 
1882,  335.)  7.  As  river  bars.  This  regards  the  lenses  as  due  to 
the  concentration  of  magnetite  sands  in  rivers  or  flowing  currents. 
Hence  the  overlapping  lenses,  the  arrangement  in  ranges  or  on  lines 
of  drainage,  and  the  occasional  swirling  curves  found  on  the  feather- 
ing edges  of  lenses,  as  in  the  Dickerson  mine,  Ferromont,  N.  J. 
(See  H.  S.  Munroe,  School  of  Mines  Quarterly,  Vol.  III.,  p.  43 — an 
important  paper.)  It  is  also  reasonable  to  suppose  that  lakes  or 
still  bodies  of  water  may  have  occurred  along  such  rivers,  and  have 
occasioned  the  accumulation.  (As  segregated  veins,  see  Addenda.) 

Several  other  hypotheses  with  small  claims  to  credibility  could 
be  cited.  They  are  outlined  at  length  in  J3ull.  VI.,  Minn.  Geol. 
Survey,  p.  224,  but  in  this  place  there  has  been  no  desire  to  take  up 
any  but  those  deserving  serious  attention.  It  may  be  said  that  while 
one  or  the  other  of  the  above  seven  hypotheses  may  in  instances  be 
applied  with  reason,  yet  most  candid  observers  with  widened  ex- 
perience have  grown  less  positive  in  asserting  them  as  axiomatic. 

2.03.15.  Of  importance  in  connection  with  iron  ore  deposits 
are  the  recent  studies  of  the  distribution  of  phosphorus  along 
certain  lines  in  the  beds,  by  a  knowledge  of  which  it  is  possible  to 
keep  more  valuable  Bessemer  ore  distinct  from  less  valuable. 
Such  lines  have  been  found  in  Michigan,  and  have  been  called 
by  Mr.  Browne  "  isochemic  lines."  Though  less  marked  at  the 
Burden  mines  (Example  3),  the  phosphorus  was  characteristic  of 
certain  varieties  of  the  ore.  Much  work  has  also  been  done  on 
the  same  question  at  Iron  Mountain,  Mo.1 

1  D.  H.  Browne,  "  On  the  Distribution  of  Phosphorus  at  the  Luddicg- 


MAGNETITE  AND  PYRITE. 


131 


ANALYSES  OF   MAGNETITES. 

(Caution  in  interpreting  analyses  is  again  emphasized  asunder  2.01.26.) 


Fe. 

P. 

S. 

TiO2. 

Si02. 

Ala03 

'Canada  (Rideau  Canal)                .  . 

50  23 

9  gO 

Chateau^  ay  mines,  N.  Y  .,  lump.  . 
"                "       concentrated. 
Mineville   N  Y  (Min^  21) 

49.24 
66.00 
62  10 

0.029 
0003 
1  198 

0.052 

18.447 

Orange  County,  N.   Y.  (Forest  of 

63  00 

0.621 

0.148 

Putnam  Countv  N  Y 

48  82 

0  021 

0  08 

11  75 

3  50 

New  Jersey  (Hibernia)  

53  75 

0  364 

Cornwall,  Peon  

42.7 

0.135 

0  620 

3  411 

64.64 

0.004 

0.115 

Colorado  (Calumet)  .    

49.23 

0.026 

3.85 

"         (Iron  King)   

58.75 

0.044 

0  123 

Utah  (Iron  (  'ounty)  

62.6 

0.12 

4  80 

•California  (Gold  Valley)  

60.68 

10  87 

PYRITE. 

2.03.16.  Example   16.    Pyrite  Beds.     Beds   (veins)   of  pyrite, 
often  of  lenticular  shape  and  of  character  frequently  analogous  to 
magnetite  deposits,  in  slates  and  schists  of  the  Cambro-Silurian  or 
Huronian  systems,  and  less  often  in  gneiss  of  the  Archaean.    Slates 
are  most  common,  and  gneiss  least  so.     They  extend  from  Canada 
down   the  Appalachians  to   Alabama,   being  found  at  Capelton, 
Quebec  ;  Milan,  N.  H.  ;   Vershire,  Vt.  ;  Charlemont,  Mass.   (An- 
thony's Nose,  N.  Y.,  and  the  Gap  mine,  Pennsylvania,  being  pyr- 
rhotite,  will  be  mentioned  under  "  Nickel "  with  other  similar  oc- 
currences) ;  Louisa  County,  Virginia  ;  Ducktown,  Tenn.  (see  above, 
Fig.   6),  and  at  many  points  less  well  known  in  Alabama.     Also 
at  Sudbury,  north   of  Lake  Superior,   recent  developments  have 
shown  an  enormous  deposit,  specially  discussed  under  "  Nickel." 

2.03.17.  The  ore  bodies  lie  interbedded  in  the  slates,  and  often 
the  different  lenses  overlap  and  succeed  each  other  in  the  footwall 
and  exhibit  all  the  phenomena  cited  under  magnetites.     Chalco- 
pyrite  is  usually  present  in  small  amount,  and  where  the   copper 
reaches   3  to   5%  they  are  valuable  as  copper  ores.       (See  under 


ton  Mines."  etc.,  M.  E.,  XVII.,  p.  616.  I.  Olmsted,  "  The  Distribution  of 
Phosphorus  in  the  Hudson  River  Carbonates,"  M.  E.,  Colorado  meeting, 
June,  1889.  W.  B.  Potter,  Analyses  of  Missouri  ore  published  in  Mineral 
Resources,  1890,  p.  47. 


KEMP'S    ORE  DEPOSITS. 


"  Copper.")  At  present  they  are  of  increasing  importance  as  a 
source  of  sulphuric  acid  fumes  for  the  manufacture  of  sulphuric 
acid.  Small  amounts  of  lead  and  zinc  sulphide  are  often  present, 


FIG.  29. — Illustration  of  overlapping  lenses  of  py rite.    After  A.  F.  Wendt, 
School  of  Mines  Quarterly,  Vol.  VII. ,  1886, 

rarely  a  little  silver.  Nickel  and  cobalt  occur  especially  in  the  pyr- 
rhotitic  varieties.  They  are  worthless  as  a  source  of  iron.  The 
auriferous  pyrites  of  the  Southern  States  will  be  mentioned  under 
«  Gold." 

2.03.18.  They  may  have  accumulated  in  a  way  analogous  to 
the  bog  ore  hypothesis,  cited  under  "  Magnetite  ;  "  but  instead  of 
the  iron  being  precipitated  as  oxide,  it  has  probably  come  down  as 
sulphide  from  the  influence  of  decaying  organic  matter,  and  has 
subsequently  shared  in  the  metamorphism  and  solidification  of  the 
wall  rock.  At  the  same  time  it  must  be  admitted  to  be  an  obscure 
point.  By  many  they  are  thought,  with  more  reason,  to  have 
originated  like  a  bedded  fissure  vein  whose  overlapping,  lenticular 
cavities  have  been  formed  by  the  buckling  of  folded  schists.1  (Cf. 
"Gold  Quartz,"  as  later  described.) 


1  W.  H.  Adams,  "  The  Pyrites  Deposits  of  Louisa  County,  Virginia, " 
M.  E.,  XII.,  p.  527.  C.  R.  Boyd,  "The  Utilization  of  the  Iron  and  Copper 
Sulphides  of  Virginia,  North  Carolina,  and  Tennessee,"  M.  E.,  XIV.,  p.  81;. 
Resources  of  S.  W.  Virginia.  H.  Credner,  "  At  St.  Anthony's  Nose,  Hudson 
River,"  B.  und  H.  Zeit.,  1866,  p.  17  ;  "Pyrite  in  Virginia,  Tennessee,  and 
Georgia,"  B.  und  H.  Zeit.,  1871,  p.  370.  H.  T.  Davis,  Mineral  Resources 
of  the  U.  S.,  1885,  p.  501.  H.  M.  Howe,  "  The  Copper  Mines  of  Vermont," 
M.  E.,  Baltimore  meeting,  February,  1892.  William  Marty n,  Mineral  Re- 


MAGNETITE  AND  PYRITE.  133 

2.03.19.  The  relative  importance  of  the  different  kinds  of  ore  is 
shown  by  the  following  tables  for  1880  and  1890.  The  increase  in 
red  hematite  is  due  to  the  Lake  Superior  region  and  to  Alabama. 

Per  cent.  Per  cent. 

1880.  of  Total.  1890.  of  Total. 

Red  hematite 2,512;,'  1,'J  ol  5.1  10,527,650  65.65 

Magnetite 2,390,389  29.98  2,570,838  16.03 

Brown  hematite 2,149,417  26.95  2,559,938  15.96 

Carbonate 922,288  11.56  377,617  2.36 


7,974,806  100.00  16,036,043  100.00 

As  indicating  the  relative  importance  of  the  different  mining 
regions,  the  following  figures  are  of  interest.  No  individual  State 
producing  less  than  100,000  tons  is  given. 

States.  Total  in  1830.  States.  Totalinim. 

Michigan 7,141,656  New  Jersey 495,808 

Alabama 1,897815  Tennessee 465,695 

Pennsylvania 1,361,622  Georgia 244.088 

New  York 1,253,393  Missouri 181,690 

Wisconsin 948,965  Ohio 169,088 

Minnesota 891,910  Colorado 114  275 

Virginia 543,583  All  the  others 326,455 

Grand  total 16,036,043 

sources,  1883-84,  p.  877.  E.  C.  Moxham,  "The  Great  Gossan  Lead  of  Vir- 
ginia" (altered  pyrite  in  Carroll  County),  M.  E.,  February,  1892.  A.  F. 
Wendt,  "  The  Pyrites  Deposits  of  the  Alleghanies,"  School  of  Mines  Quar- 
terly, Vol.  VII. ,  and  separate  reprint ;  also  Engineering  and  Mining 
Journal,  June  5,  1886,  p.  22  and  elsewhere.  Rec.  H.  A.  Wheeler,  "Cop- 
per Deposits  of  Vermont,"  School  of  Mines  Quarterly,  IV.  210. 


CHAPTER   IV. 

COPPER. 

2.04.01.  Copper  Ores. 

TABLE    OF    ANALYSES. 

Cu.  S.  Fe. 

Native  copper  (generally  with  some  silver) 100. 

Chalcocite,  Cu2S 79.8          20.2 

Chalcopyrite,  CuFeS2 34.6          34.9        30.5 

Bornite,  Cu3FeS3 61.79        25.8        11.7 

Tetrahedrite,  4CuS8Sb2S3  (variable)  26.50  Sb' 36.40        26,7          1 .39 

Enargite,  Cu3AsS4(As.l9.1) 48.4          32.5 

Cuprite,  Cu 2O 88 . 8 

Melaconite  (tenorite),  CuO 79.86 

Malachite,  2CuO+CO2+H2O 57.4 

Azunte,  3CuO+CO2+H2O 55.0 

Chrysocolla,  CuO+SiO2+2H2O 36.1 

2.04.02.  Example   16,  Continued.     Pyrite  or  pyrrhotite  beds 
(veins),  with   intermingled   ehalcopyrite.     Whether  the   deposits 
are  true  beds  or  veins  parallel  with  the  stratification  is  as  yet  a 
matter  of  dispute.     The  resemblance  to  magnetite  argues  a  bed, 
and  this  view  is  generally  taken  by  German  writers.     The  Cali- 
fornia mines  occur  closely  associated  with  the  auriferous  (pyritous) 
quartz  bodies,  which  are  always  esteemed  veins.     The  interbedded 
lenticular  deposits  are  placed  by  themselves  as  the  main  example. 
The  undoubted  veins  like  Ore  Knob,  N.    C.,    are   then   made   a 
sub-example.      Pyrites    and    pyrrhotite    (called    mundic   by   the 
miners)  are  the  principal  constituents  of  such  bodies,  but  often  the 
copper  reaches  4  to  5#,  and  then  they  are  valuable   for  copper. 
The  ores  are  often  roasted  for  sulphurous  fumes  in  acid  works, 
and  afterward  the  residues  are  returned  to  the  copper  smelters. 
They  have  been  or  are  being  worked  for  this  metal  at  Capel- 
ton,  Quebec,  just  north  of  Vermont.     At  Milan,  N.  H.,  there  are 
several  deposits  in  argillitic  schists,  and  in  the  same  region  are 
numerous  other  locations.     At  Yershire,  Vt.,  there  is  a  belt  some 


COPPER.  135 

j 

twenty  miles  long  with  three  principal  mining  points.  Of  these 
the  middle  one,  containing  the  Ely  mine,  is  the  largest.  Two 
beds  of  ore  occur,  separated  by  from  10  to  20  feet  of  schists.  The 
lower  averages  about  four  feet,  but  fluctuates;  the  upper  is  still 
more  variable,  and  may  reach  25  feet.  They  are  both  formed  by 
a  succession  of  thin  lenses.  The  ore  is  chalcopyrite,  mingled  with 
pyrrhotite  and  quartz.  At  Ducktown,  Tenn.,  which  is  in  the  ex- 
treme southeast  corner  of  the  State,  there  are  three  ranges  of  ore 
hills  in  a  width  of  a  mile.  The  outcrop  is  marked  by  great  masses 
of  gossan,  and  below  this,  and  along  the  contact  with  the  sulphides, 
was  found  the  rich  black  ore  which  gave  the  early  impetus  to  the 
mines.  When  this  was  exhausted  the  sulphides  alone  remained. 
They  consist  of  chalcopyrite  and  pyrrhotite,  with  considerable 
quartz  and  country  rock,  less  often  calcite.  (See  Fig.  7,  p.  39.)  . 

2.04.03.  Example  IQa.  Ore  Knob,  N.  C.  This  is  described  by 
Kerr  as  a  true  fissure  vein,  extending  2000  feet  on  the  strike,  which 
is  parallel  to  that  of  the  gneiss,  but  cutting  the  dip  in  descent. 
The  width  averaged  about  10  feet.  The  gossan  extended  to  a 
depth  of  50  feet,  and  furnished  the  usual  body  of  rich  ore  at  the 
contact  with  the  sulphides.  It  has  not  been  operated  for  some 
years.1 

1  J.  T.  Bailey,  "  The  Copper  Deposits  of  Adams  County,  Pennsyl- 
vania," Engineering  and  Mining  Journal,  Feb.  17,  1883,  p.  88.  H.  Cred- 
ner,  "On  Ducktown,  Tenn.," B.  und  H.  Zeit.,  1867,  p.  8.  Engineering  and 
Mining  Journal,  Nov.  6, 1886,  p.  327  (contains  "  The  Elizabeth  Copper  Mines, 
Vermont"  ;)  see  also  April,  1886.  P.  Fraser,  "Some  Copper  Deposits  of 
Carroll  County,  Maryland,"  M.  E.,  IX.  33;  "  Hypothesis  of  the  Structure  of 
the  Copper  Belt  of  the  South  Mountain,  Pennsylvania,"  M.  E.,  XII.  C.  H. 
Henderson,  "Copper  Deposits  of  the  South  Mountain,  Pennsylvania," 
M.  E.,  XII.  85.  C.  H.  Hitchcock,  Geol.  of  N.  H.,  Vol.  III.,  Part  III.,  p.  47. 
H.  M.  Howe,  "The  Copper  Mines  of  Vermont, "  M.  E.,  February,  1892. 
T.  S.  Hunt,  "Ore  Knob  and  Some  Related  Deposits,"  M.  E.,  II.  125. 
Kleinschmidt  (on  Virginia,  Tennessee,  and  North  Carolina),  Gangstudien, 
Vol.  III. ,  p.  256.  (A  good,  short,  but  old  account.)  E.  E.  Olcott,  "  Ore  Knob 
Copper  Mine  and  Reduction  Works,"  M.  E.,  III.  391.  Rec.  Richardson, 
'•Copper  Ore  of  Stafford,  Vt.,  Amer.  Jour.  Sci.,  I.  21,  383.  Tripple  and 
Credner,  "Report  on  the  Ducktown  Region  to  the  American  Bureau  of 
Mines,"  1866.  M.  Tuomey,  "A  Brief  Note  of  Some  Facts  Connected  with 
the  Ducktown  (Tenn.)  Copper  Mines,"  Amer.  Jour.  Sci.,  II.  19,  181.  A.  F. 
Wendt,  "  The  Pyrites  Deposits  of  the  Alleghanies,"  School  of  Mines  Quar- 
terly, Vol.  VII.,  1886  ;  Engineering  and  Mining  Journal,  July  10  and  fol- 
lowing, 1886.  Rec.  H.  A.  Wheeler,  "Copper  Deposits  of  Vermont," 
School  of  Mines  Quarterly,  Vol.  IV.,  219.  Rec. 


136  KEMP'S   ORE  DEPOSITS. 

2.04.04.  Example   IGb.     Spenceviile,    Cal.     Beds   of    pyrites 
with  considerable  chalcopyrite,  in  Jurassic  slates,  on  the  western 
slopes  of  the  Sierra  Nevada.    The  Jurassic  slates  along  the  western 
Sierras  contain,  in  the  gold  belt,  some  interbedded  deposits  of  py- 
rite  with  considerable  chalcopyrite  intermingled.     The  most  im- 
portant are  at  Newton,  Amador  County,  Copperopolis  and  Campo 
Seco,  Calaveras  County,  and  Spenceviile,  Nevada  County.     At  the 
first   named  there  is  a  body  of    sulphides    7  to  8  feet  wide    and 
proved  about  400  feet.     In  the  adjoining  county  of  Calaveras,  the 
Union  mine,  at  Copperopolis,  is  on  a  very  large  body  of  sulphides, 
which  impregnate  the   slates  on  each  side  without  forming  a  very 
sharp  foot  or  hanging  wall.     The  Campo  Seco  deposits  are  on  the 
same  general  line  as  the  Copperopolis.     The  extension  passes  also 
through  those  at  Newton.     A  long  distance  north  are  the  mines  in 
Spenceviile,  Nevada  County.     The  general  geology  is  similar,  and 
the  ore  body  large.    It  affords  from  3.50  to  5.50#  copper.    All  these 
ores  are  worked  by  wet  methods.1 

NOTE. — For  Examples  IQc  and  IQd  see  under  "Nickel." 

2.04.05.  Example  17.     Butte,  Mont.     Veins  originally  fissures, 
or  shear  zones,  but  greatly  enlarged  by  replacement  of  the  walls 
with  ore,  filled  with  copper  sulphides,  bornite,  chalcopyrite,  etc.,  in 
a  siliceous  gangue.     Much  silver  is  associated  with  the  copper.     At 
Butte  there  is  a  north  and  south  valley  six  miles  wide  between  high 
granite  ridges  on  the  east  and  lower  rhyolite  ridges   on  the  west. 
The  bounding  heights  north   and  south  are    still  farther  distant. 
Near  the  middle  of  this  valley  the  butte  of  rhyolite  arises  which 
gives  the  town  its  name.    Silver  Bow  Creek,  which  gives  the  name 
to  the  county,  flows  south  along  the  eastern  ridge  and  then  bends 
westward  at  a  point  south  of  the  butte,  and,  after  flowing  directly 
across  the  valley,  leaves  it  through  the  western  ridge.     In  the  half 
of  the  valley  east  of  the  meridian  of  the  butte  is  a  very  dark  basic 
granite,    and    also   in   the    extreme    west.     It  consists  of   quartz, 
orthoclase,  plagioclase,  and  an  unusual  amount  of  mica,  augite,  and 
hornblende.     In  the  part  west  and  south  of  the  butte  is  a  highly 


1  J.  E.  Ellis,  "On  the  Spenceviile  Mines,"  Mineral  Resources  U.  S., 
1884,  p.  340.  H.  G.  Hanks,  Rep.  California  State  Mineralogist,  1884,  p. 
148.  J.  B.  Hobson,  "On  Spenceviile,"  Rep.  California  State  Mineral- 
ogist, 1890,  p.  392.  William  Irelan,  Jr.,  "On  Calaveras  County  Mines," 
Rep.  California  State  Mineralogist,  1888,  pp.  150-153.  "  On  the  Newton 
Mines,"  ibid.,  p.  106. 


COPPER.  137 

acidic,  light-colored  granite,  which  consists  of  quartz  and  ortho- 
clase  feldspar  with  a  very  little  biotite.  Dikes  of  quartz  porphyry 
penetrate  the  basic  granite,  and  dikes  of  rhyolite  are  also  found 
associated  with  the  ore  bodies.  Tongues  of  rhyolite  are  met,  ap- 
parently offshoots  of  the  butte. 

2.04.06.  East  of  the  butte  and  in  the  coarse  granite  are  found 
the  older  mines  along  two  strongly  contrasted  east  and  west  zones. 
A  second,  later-developed,  group  is  west  of  the  butte  in  the  acidic 
granite.  Of  the  former,  the  southern  affords  argentiferous  copper 
ores,  consisting  of  chalcocite,  bornite,  chalcopyrite,  enargite,  and 
pyrite  in  a  siliceous  gangue.  The  northern  zone  contains  silver 
ores,  chiefly  sulphides  of  silver,  lead,  zinc,  and  iron,  in  a  siliceous 
gangue  with  much  rhodonite.  Strangely  enough,  hardly  any  cop- 
per occurs  in  the  silver  zone,  and  no  manganese  is  met  in  the  copper 
zone,  except  in  the  Gagnon  vein,  which  also  contains  zinc.  The 
silver  zone  is  mentioned  again  under  "  Silver."  The  zone  west  of 
the  butte  is  silver-bearing  with  manganese.  The  occurrence  of 
these  two  parallel  systems  of  fissures  in  the  same  country  rock  and 
not  far  from  each  other,  yet  filled  with  such  contrasted  ores,  is  a 
very  remarkable  phenomenon  and  points  to  different  and — at  least 
for  one  of  them — deep-seated  sources  of  the  ores. 

2.04.0V.  The  ore  bodies  do  not,  in  general,  present  very  sharply 
defined  walls,  but  the  ores  fade  into  the  wall  rock.  From  this 
S.  F.  Emmons  has  suggested  that  they  have  formed  along  a  series 
of  small  fissures  marking  some  line  of  disturbance,  and  not  from 
a  general  faulting,  and  have  enlarged  the  original  channels  by  re- 
placement of  the  walls.  It  would  seem  probable  that  the  frequent 
dikes  are  connected  with  the  butte,  or  with  the  same  parent  body 
that  sent  it  off.  The  same  eruptive  activity  probably  shattered  the 
rock  along  the  zones.  In  this  event  it  must  have  been  from  an 
easterly  offshoot  of  the  western  rhyolite  area,  and  have  operated 
with  the  same  fissuring  action  which  attends  earthquakes  from  the 
intrusion  of  subterranean  dikes.  The  Butte  district  alone  rivals 
the  Lake  Superior  copper  mines  in  output,  and  has  in  recent  years 
surpassed  them.  Reference  will  again  \Q  made  to  this  region 
under  "  Silver."  l 


1  "  Butte  Copper  Mines,"  Engineering  and  Mining  Journal,  June  19, 
1886,  p.  445;  also  April  24,  1886,  p.  299.  S.  F.  Emmons,  "Notes  on  the 
Geology  of  Butte,  Mont.,"  M.  E.,  XVI.  49.  Rec.  Richard  Pearce,  "The 
Association  of  Minerals  in  the  Gagnon  Vein,  Butte  City,  Mont.,"  M.  E.> 


138 


KEMPS   ORE  DEPOSITS. 


2.04.08.  Example  l7a.  Gilpin  County,  Colorado.  Veins 
of  pyrite  and  chalcopyrite,  replacing  gneiss  (the  rock  may  be 
granite),  and  dikes  of  quartz-porphyry,  and  felsite  along  the  planes 
of  joints,  which  cross  the  gneiss  (or  granite)  perpendicularly  to 
the  laminations.  The  veins  are  highly  auriferous  and  are  worked 
primarily  for  gold,  the  copper  being  produced  as  a  by-product. 
The  concentrates  from  the  stamps  are  afterward  treated  for  cop- 
per. The  veins  occupy  an  area  of  only  about  a  mile  and  a  half 
in  diameter,  centering  about  Central  City.  They  show  little  indica- 
tion of  filling  a  fissure,  as  usually  understood,  but  follow  the  cleav- 


PIG.  30.— Cross  section  of  the  Bob-tail  mine,  Central  City,  Colo.     After 
F.  M.  Endlich,  Hayderis  Survey,  1873,  p.  286. 

age  joints  of  the  gneiss  and  replace  the  country  rock  on  each  side 
of  them.  The  joints  also  cross  the  porphyry  dikes,  and  the  veins 
are  often  in  the  latter  rock.  They  are  closely  related  in  structure 
and  origin  to  the  galena  veins  of  the  neighboring  Clear  Creek 
County,  which  are  referred  to  under  "Silver,"  but  the  contrast 
in  mineral  contents  between  the  two  is  very  marked.  They  were 
the  basis  of  the  first  extensive  deep  mining  in  Colorado,  and  were 
located  through  the  placer  deposits  in  the  neighboring  gulches.1 


XVI.  62.  "On  the  Occurrence  of  Goslarite  in  the  Gagnon  Mine,  Butte 
City,"Proc.  Colo.  Sci.,  Vol.  II.,  Part  I.,  p.  12.  E.  D.  Peters,  Mineral  Re- 
sources of  the  U.  S.,  1883-84,  p.  374.  A.  Williams  and  E.  D.  Peters,  "On 
Butte,  Mont.,"  Engineering  and  Mining  Journal,  March  23,  1885,  p.  208. 

1  S  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  68.  The  veins  are  de- 
scribed as  cited  above.  J.  D.  Hague,  Fortieth  Parallel  Survey,  III.,  p.  493. 
The  veins  are  called  fissure  veins  by  Mr.  Hague.  A.  Lakes,  Ann.  Rep. 


COPPER.  139 

2.04.09.  Example  lib.    Llano  County,  Texas.    Impregnations  in 
granite,    and  veins  with  quartz  gangue  in  granite,  carrying  car- 
bonates above,  but  sulphurets  and  tetrahedrite  with  some  gold  and 
silver  below.     Contact  deposits  between  slates  and  granite  are  also 
known.     It  is  not  demonstrated  as  yet  whether  the  ores  are  to  be 
actually  productive. l 

2.04.10.  Example  18.     Keweenaw  Point,  Mich.     Native  cop- 
per,   with    some   silver,  in    both    sedimentary    and   interstratified 
igneous  rocks  of  the  Keweenawan  system.     The  metal  occurs  as  a 
cement,  binding  together  and  replacing  the  pebbles  of  a  porphyry 
conglomerate  ;  or  filling  the  amygdules  in  the  upper  portions  of 
the  interbedded  sheets  of  massive  rocks  ;  or  as  irregular  masses, 
sometimes  of  enormous  size,  in  veins,  with  a  gangue  of  calcite,  epi- 
dote,  and  various  zeolites;  or  in  irregular  masses  along  the  contacts 
between  the  sedimentary  and  igneous  rocks. 

2.04.11.  The    rocks   of    the    Keweenawan    system    are    most 
strongly  developed  on  the  south  shore  of  Lake  Superior,  especially 
in  Keweenaw  Point,  which  juts  out  northwesterly,  cutting  the  lake 
into  t\vo  nearly  equal  portions.     They  extend   some  distance  east 
and  west  and  are  also  known  on  the  north  shore.     They  consist  of 
sandstone  and  thin  beds  of  conglomerate,  interstratified  with  sheets 
of  diabase,  both  compact  and    amygdaloidal,  and  of  melaphyre. 
They  are  succeeded  on  the  east  by  the  Eastern  Sandstone,  which 
on  the  south  shore  in  some  places  abuts  unconformably  against 
them,  and  in  others  passes  under  them  from  an  overthrust  fault. 

On  Keweenaw  Point  they  dip  northeasterly  and  pass  under 
Lake  Superior  to  reappear  with  a  southeasterly  dip  on  Isle  Royale 
and  the  Canadian  shore.  Western  Lake  Superior  occupies  this 
synclinal  trough.  In  Keweenaw  Point  the  dip  is  greatest  on  the 
southeast,  being  about  60°  at  Hancock.  To  the  northwest  it 
gradually  flattens  to  30°  or  less  on  the  lake  shore.  (For  the  gen- 
eral geology  of  the  neighboring  region  see  under  Example  9.) 

It  is  interesting  to  note  that  the  early  investigators  of  the 
geology  of  this  country  drew  a  parallel  between  the  sandstones 
and  traps  of  Lake  Superior  and  the  similar  Triassic  deposits  of  the 


Col.  State  School  of  Mines,  1887,  p.  cii.  A.  W.  Rogrers,  '-The  Mines  and 
Mills  of  Gilpin  County,  Colorado,"  M.  E.,  II.  23.  Further  references  will 
be  found  under  "Silver  and  Gold  in  Colorado." 

1  T.  B.  Comstock,  First  Ann.  Rep.  Texas  Geol.  Survey,  1889,  p.  334. 
W.  H.  Streeruwitz,  in  Mineral  Resources  of  the  U.  S.,  1884,  p.  342. 


COPPER.  141 

Atlantic  coast  (see  Example  21),  even  going  so  far  as  to  regard 
the  former  as  the  western  equivalent  of  the  latter.1 

There  are  three  principal  mining  districts — the  Keweenaw 
Point,  on  the  end  of  the  Point  ;  the  Portage  Lake,  in  the  middle  ; 
and  the  Ontonagon,  at  the  western  base.  Mines  have  also  been 
worked  on  Isle  Royale,  and  copper  is  found  in  small  amounts 
on  the  north  shore.  The  Portage  Lake  district  is  now  the  princi- 
pal and  almost  the  only  producer.  In  the  first-named  district  most 
of  the  mines  are  on  original  fissures,  which  have  later  become 
much  enlarged  by  the  alteration  of  the  walls.  They  are  usually 
from  1  to  3  feet  broad,  but  may  reach  10,  20,  and  30  feet,  this  last 
in  the  looser  textured  rocks.  These  expansions  are  also  richer  in 
copper.  The  veins  stand  nearly  vertical  and  cross  the  beds  at  right 
angles.  They  were  the  earliest  discovered  and  the  first  to  be  ex- 
tensively worked.  The  metallic  masses,  both  large  .  and  small, 
occur  distributed  through  the  gangue.  The  best  known  mines  of 
the  district  are  the  Cliff,  the  Phoenix,  and  the  Copper  Falls. 

2.04.12.  In  the  Portage  Lake  district  the  mines  are  either  in 
conglomerate  (Calumet  and  Hecla,  Tamarack,  Peninsula,  etc.)  or 
in  amygdaloidal,  strongly  altered  diabase,  certain  very  scoriaceous 
sheets  of  which  are  known  as  ash-beds  (Quincy,  Franklin,  Atlantic, 
etc.).    In  the  conglomerates  the  copper  has  replaced  the  finer  frag- 
ments, so  as  to  appear  like  a  cement,  and  often  the  boulders  them- 
selves, or  particular  minerals  in  them,  are  permeated  with  copper. 
The   amygdaloids  have  copper  in  their    small  cavities,  but  in  the 
open  or  shattered  rock  it  fills  all  manner  of  irregular  spaces,  often 
in    fragments   of   great   size.     It  is   associated  with    calcite,    the 
zeolites    (often    of  great  beauty),  epidote,   and  chlorite   (the  last 
containing  Fe2O3). 

2.04.13.  In  the  Ontonagon  district  the  copper  follows  planes 
approximately  parallel  to  the  bedding  of  the  sandstones  and  igneous 
rocks,  and  in  one  case  at  least  (the  National  mine)  along  the  con- 
tact between  the  two.     The  copper  is  quite  irregular  in  its  distri- 
bution, but  has  the  same  associates  that  are  mentioned  above. 

2.04.14.  In  their  practical  bearings  the  mines  are  classed  as 
Mass  Mines,  Amygdaloid  Mines,  and  Conglomerate  Mines,  accord- 
ing to  thje'size  of  the  masses  of  copper  or  to  the  character  of  the 
inclosing  rock. 

2.04.15.  On  the  Origin  of  the  Copper. — The  original  source  of 

1  C.  T.  Jackson,  Amer.  Jour.  Sci.,  i.,  XLIX.,  1845,  pp.  81-93. 


142  KEMPS   ORE  DEPOSITS. 

the  copper  was  thought  by  the  earlier  investigators  to  be  in  the 
eruptive  rocks  themselves,  and  that  with  them  it  had  come  in  some 
form  to  the  surface  and  had  been  subsequently  concentrated  in  the 
cavities.  Pumpelly  has  referred  it  to  copper  sulphides  distributed 
through  the  sedimentary,  as  well  as  the  massive  rocks  from  which 
the  circulating  waters  have  leached  it  out  as  carbonate,  silicate, 
and  sulphate.  Although  the  traps  are  said  by  Irving  to  be  devoid 
of  copper,  except  as  a  secondary  introduction,  it  would  be  interest- 
ing to  test  their  basic  minerals  for  the  metal  in  a  large  way,  as  has 
been  so  successfully  done  by  Sandberger  on  other  rocks.  It  is 
probable  that  these  may  be  its  source. 

Irving  states  that  the  coarse  basic  gabbros  of  the  system  con- 
tain chalcopyrite,  but  they  do  not  occur  near  the  productive  mines. 
The  electro-chemical  hypothesis  of  deposition  was  earliest  advo- 
cated (Foster  and  Whitney),  and  on  account  of  the  electrolytic 
properties  of  the  two  metals  copper  and  silver,  at  first  thought  it 
has  strong  claims  to  probability.  Still  the  unsatisfactory  charac- 
ter of  all  experiments  made  in  other  regions  to  detect  such  action 
militates  against  it.  Pumpelly,  however,  has  worked  out  an  ex- 
planation much  more  likely  to  be  the  true  one.  He  found,  on 
studying  the  mineralogical  changes  which  have  taken  place  in  the 
rocks,  that  the  alteration  had  been  very  extensive  ;  that  it  had 
proceeded  through  a  series  of  minerals  involving  at  one  stage  a 
change  in  the  iron  present  from  protoxide  to  sesquioxide  (which 
would  occasion  a  reducing  action),  and  that  at  this  stage  the  cop- 
per was  deposited.  In  two  fissure  veins  near  Portage  Lake  sul- 
phides and  arsenides  of  copper  occur,  and  in  a  vein  near  Lac  la 
Belle,  on  the  Mendota  property,  a  little  chalcocite  has  been  found. 
These  are  the  only  instances,  yet  recorded,  of  sulphides  or  related 
compounds  of  copper  in  the  district.  A  pocket  of  melaconite,  the 
black  oxide,  was  opened  in  the  early  days  at  Copper  Harbor. 

The  discovery  of  copper  dates  back  to  the  explorations  of  the 
French,  who  in  the  seventeenth  century  left  the  settlements  on  the 
lower  St.  Lawrence  and  penetrated  the  Great  Lakes.  The  country 
was  the  scene  of  a  great  mining  excitement  in  the  forties.  After 
many  vicissitudes  and  exploded  schemes  the  district  settled  down 
to  the  largest  production  of  any  American  region.  Within  the 
last  few  years,  however,  Butte,  Mont.,  has  temporarily  exceeded  it. 
Many  interesting  traces  of  prehistoric  mining  were  found  by  the 
early  explorers,  for  the  copper  was  a  much  prized  commodity 
among  the  aborigines. 


COPPER.  143 

I 

2.04.16.  Some  important  mining  for  copper  has  been  done  on 
Isle  Royale,  along  the  Canadian   shore,  and  in  Minnesota,  but  al- 
though Keweenawan  rocks  are  in  great  force,  no  large  amount  of 
the  metal  has  been  found.1 

2.04.17.  Example  19.     St.    Genevieve,  Mo.     Beds  of    chalco- 
pyrite  associated  with  chert  in  magnesian  limestone  of  the  Lower 
Silurian  system.     St.  Genevieve  is  situated  on  the  Mississippi,  about 
forty  miles  south  of  St.  Louis.     The  Second  Magnesian  Limestone 
of  the  Lower  Silurian  outcrops,  with   the    Carboniferous   on   the 
north,  and  more  or  less  Quaternary  in  the  vicinity.     There  are  two 
nearly  horizontal  beds  of  ore,  of  widths  varying  between  three 


1  It  would  be  impossible  and  undesirable  to  give  in  this  place  com- 
plete references  to  the  literature.     Such  bibliography  will  be  found  in  Irv- 
ing's  monograph,  and  in  Wadsworth's.    The  more  important  papers  are 
given  below,  with  some  additions  to  the  lists  mentioned  above. 
Blake,  W.  P.,  "Mass  Copper  of  the  Lake  Superior  Mines,"  etc.,  M.  E., 

IV.  110. 
Credner,  H.,  On  the  geology,  etc.,  Neues  Jahrbuch,  1869,  p.  1. 

Engineering  and  Mining  Journal,  "History  of  Copper  Mining  in  the 

Lake  Superior  District,"  March  18,  1882,  p.  141. 

Foster  and  Whitney,  Report  on  the  Lake  Superior  Copper  Lands,  1850. 
Hall,  C.  W.,  "A  Brief  History  of  Copper  Mining  in  Minnesota,"  Bull. 

Minn.  Acad.  Nat.  ScL,  Vol.  III.,  No.  1,  p.  105. 
Irving,  R.  D.,  "  The  Copper-bearing  Rocks  of  Lake  Superior,"  Monograph 

V.,  U.  S.  Geol.  Survey,  especially  p.  419.     Rec. 
Jackson,  C.  T.,  "The  Great  Copper-bearing  Belt  of  Canada,"  Boston  Soc. 

Nat.  Hist.,  IX.  202. 
Lawson,  A.  C.,  "Note  on  the  Occurrence  of  Native  Copper  in  the  Animi- 

kie  Rocks  of  Thunder  Bay,"  Amer.  Geol.,  V.  174, 
Poole,  H.,  "  Michipicoten  Island  and  its  Copper  Mines,"  Engineering  and 

Mining  Journal,  Aug.  6,  1892,  p.  125 ;  Sept.  3,  p.  220. 
Pumpelly,  R.,  Geol.  Survey  of  Mich.,  1873,  Vol.  I. 

"  On  the  Origin  of  the  Copper,"  Amer.  Jour.  Sci.,  U.,  III.   183-195,  243- 

253,  347-353.     Rec.     A  later  and  fuller  paper  is  in  Proc.   Amer. 

Acad.,  1878,  Vol.  XIII.,  p.  233. 
Wadsworth,  M.  E.,  Notes  on  the  Geology  of  the  Iron  and  Copper  Districts 

of  Lake  Superior.     Cambridge,  1880. 
Whitney,  J.  D.,  "  On  the  Black  Oxide  of  Copper  of_Lake  Superior,"  Proc. 

Boston  Soc.  Nat.  Hist.,  January,  1849,  p.  102;  Amer.  Jour.  Sci.,  ii.,, 

VIII.  273. 

Metallic  Wealth  in  the  United  States,  p.  245.    Rec. 
Whittlesey,  C.,  "On  Electrical  Deposition,"  A.  A.  A.  S.,  XXIV.  60. 
Wright,  C.  E.,  and  Lawson,  C.  D.,  Mineral  Statistics  of  Michigan.    An- 
nual. 


144 


KEMP'S    ORE  DEPOSITS. 


inches  and  several  feet.  They  lie  between  chert  seams  and  are 
associated  with  clay  and  sand.  The  ore  is  thought  by  Nicholson 
to  have  been  deposited  in  cavities  formed  by  dolomitization,  much 


2nd._Magnes"ian  Limestone 
Roof 

Limestone 

'">  Chert  seams 


>ElEEeE=£~    Sulphuret  ore 

2nd.  Magnesian  Limestone 

FIG.  32.— Cross  section  in  the  St.  Genevieve  copper  mine,  illustrating  the 
relations  of  the  ore.    After  F.  Nicholson,  M.  E.,  X.,  p.  450. 

as  is  advocated  by  Schmidt  for  the  lead  and  zinc  deposits  of  south- 
west Missouri,  and  as  is  described  under  Example  25.  For  ten 
years  the  mines  have  not  been  operated.1 


Limestone 

£§vi  Chert  and 
ore 


]ftG<  33._ Section  at  the  St.  Genevieve  mine,  illustrating  the  intimate  re- 
lations of  ore  and  chert.    After  F.  Nicholson,  M.  E.,  X.,  p.  451. 

2.04.18.  Example  20.  Arizona  Copper.  Bodies  of  oxidized 
/  -copper  ores  in  Carboniferous  limestones,  associated  with  eruptive 
)  rocks.  In  addition  to  these,  which  are  the  most  important,  are 

1  F.  Nicholson,  "Review  of  the  St.  Genevieve  Copper  District,"  M.  E., 
X.  444.  B.  F.  Shumard,  "  Observations  on  the  Geology  of  the  County  of 
St.  Genevieve,  Missouri,"  Trans.  St.  Louis  Acad.  Sci.,  Vol.  I.,  p.  40  ;  ab- 
stract in  Amer.  Jour.  Sci.,  ii.,  XXVIII.  126. 


COPPER.  145 

veins  in  eruptive  rocks,  or  in  sandstones,  or  ore  bodies  of  still 
different  character  as  set  forth  under  the  several  sub-examples. 
The  copper  districts  are  nearly  all  in  the  southeastern  part  of  the 
territory,  but  the  Black  range  is  near  the  center. 

2.04.19.  Example  20a.  Morenci.  The  Morenci  district,  known 
also  as  the  Clifton  or  Copper  Mountain,  lies  in  a  basin,  six  to  ten 
miles  across,  whose  high  surrounding  hills  consist  of  limestone, 


FIG.  34. — Geological  map  of  the  Morenci  or  Clifton  copper  district  of 
Arizona.     After  A.  F.  Wendt,  M.  E. 

probably  Lower  Carboniferous,  which  rests  on  sandstone,  and  this  on 
granite.  The  principal  mines  are  grouped  about  the  town  of  Morenci. 
Clifton  is  seven  miles  distant  at  the  point  where  the  smelter  of  the 
Arizona  Copper  Company  is  located.  In  the  basin  is  a  mass  of  por- 
phyry, containing  frequent  great  inclusions  of  limestone.  Felsite  or 
porphyry  dikes  are  also  abundant  in  the  surrounding  sedimentary 
and  granite  rocks.  Several  miles  to  the  east  there  is  an  outflow 
of  late  trachyte  and  evidence  of  recent  volcanic  action.  From  this 
it  appears  that  eruptive  phenomena  are  abundant  and  widespread. 


146  KEMPS  ORE  DEPOSITS. 

2.04.20.     The  ores  are  classified  by  Henrich  as  follows  : 

1.  Contact  deposits.     These  occur  in  a  zone  of  decomposed  and; 


UOMOFELUOW 


FIG.  &.— Vertical  section  of  Longfellow  Hill,  Clifton  district,  Arizona. 
After  Wendt,  M.  E.,  XV.  52.; 


FIG.  ^.-Horizontal  sections  of  Longfellow  ore  body.    After  Wendt. 

kaolinized  porphyry,  between  a  bluish,  fine-grained  limestone,  and 
solid  porphyry.     Many  ore  bodies,  and  probably  the  largest,  are 


COPPER. 


147 


directly  on  the  limestone,  while  others  are  surrounded  by  the  de- 
composed porphyry.  As  included  masses  of  limestone,  with  as- 
sociated ore,  are  found  in  the  decomposed  porphyry,  it  is  probable 
that  these  ore  bodies  may  have  originally  replaced  such.  The 
ores  are  jnalachite,  azurite,  cuprite  with  some  metallic  copper 
and  malachite,  in  a  gangue  principally  of  limonite.  Wad  is 
also  frequent.  Much  clay  of  a  residual  character  occurs  with  the 
ores. 

2.  Deposits  in  limestone.     These   are  closely  associated  with 


PIG.  37. — Geological  section  of  the  Metcalf  mine,  Clifton  district,  Arizona. 

After  Wendt. 

the  first  class,  and  have  apparently  formed  as  outlying  bodies  in 
the  limestone,  as  they  are  connected  by  ore  channels  with  the 
principal  lines  of  circulation  along  the  contact.  They  appear 
to  contain  more  wad  and  lime  than  the  typical  contact  de- 
posits. 

3.  Deposits  in  porphyry.  These  form  sheets  and  pockets  in 
porphyry,  or  impregnate  the  solid  rock  itself.  They  are  oxidized 
at  the  surface,  but  pass  in  depth  into  chalcocite.  The  principal 
gangue  is  kaolinized  porphyry. 

According  to  Wendt,  the  Coronado  vein  fills  a  longitudinal 
fissure  in  a  quartz  porphyry  dike.  It  afforded  chalcocite  above, 


148 


KEMP'S   ORE  DEPOSITS. 


but    passed   into    chalcopyrite    below.     Wendt    also    mentions  a, 
group  of  veins  in  granite  that  likewise  afforded  chalcocite.1 

2.04.21.  Example  20#.  The  Bisbee  district,  called  also  the 
Warren  district,  is  situated  in  the  Mule  Pass  Mountains  in 
southern  Arizona,  near  the  Mexican  line.  The  range  runs  east  and 
west  and  consists  of  beds  of  Lower  Carboniferous  limestone,  dip- 
ping away  from  a  central  mass  of  porphyritic  rock.  The  ores  are 
found  in  the  canons  on  the  south  side,  which  have  been  formed 
by  erosion,  along  the  contact  of  the  limestone  and  porphyry. 
They  are  of  the  same  oxidized  character  as  at  Morenci,  and  in  the 


FIG.  38. — Section  of  Copper  Queen  ore.  body   Bisbee.  district,  Arizona. 
After  A.  F.  Wendt,  M.  E.,  XV.  52. 

important  mines  occur  in  the  limestone.  The  ore-bearing  solutions 
seem  to  have  spread  out  chiefly  along  the  bedding  planes  and  to 
have  replaced  the  limestone  at  a  distance  from  the  contact.  The 
ore  bodies  leave  great  chambers  when  excavated  and  partake  of 
the  nature  of  bedded  veins.  Empty  caves  occur  associated  with 


1  J.  Douglass,  "  Copper  Resources  of  the  United  States,"  M.  E.,  Sep- 
tember, 1890.  Rec.  "  Arizona  Copper  and  Copper  Mines,"  Engineering 
and  Mining  Journal,  Aug.  13,  1881,  p.  103.  "  Clifton  Copper  Mines  of  Ari- 
zona," Ibid.,  Feb.  21,  1880,  p.  133.  C.  Henrich,  "  The  Copper  Ore  Deposits 
near  Morenci,  Ariz.,"  Ibid.,  March  26, 1887,  pp.  202,  219.  Rec.  A.  Wendt, 
"  Copper  .Ores  of  the  Southwest,"  M.  E.,  XV.,  p.  23.  Rec. 


I 


150  KEMP'S   ORE  DEPOSITS. 

them,  doubtless  formed,  as  at  Eureka,  Kev.  (Example  36),  by 
surface  waters  and  having  no  genetic  connection  with  the  ore. 
Evidences  of  hydrothermal  action  along  the  contact  are  abundant. 
The  Copper  Queen  and  the  Arizona  Prince  are  the  principal  mines. 
There  are  minor  deposits  in  the  porphyry  of  oxidized  ores  above, 
changing  to  chalcocite  and  this  to  chalcopyrite  in  depth.1 

2.04.22.  Example  20c.     Globe  District.     As  in  the  other  dis- 
tricts, the  most  productive  mines  are  in  limestone  near  the  contact 
with  eruptive  rocks. 

1.  Contact  deposits    in  limestone.      At  the   Globe  mines   the 
Carboniferous  limestone    abuts   against  a  great  dike   of  diorite, 
while  trachyte  and  granite  are  near.     Along  the  contact  there  is 
abundant  evidence  of  thermal  action  in  the  kaolinized  rock.     The 
great  bodies  of  oxidized  ores  are  found  on  this  contact  and  extend 
out  into  the  limestone.     The  one  on  the  Globe  claim  is  described 
by  Wendt  as  resembling  a  great  chimney. 

2.  A  fissure  vein  in  sandstone,  containing  arsenical  and  anti- 
monial  copper  ores  and  known  as  the  Old  Dominion,  was  formerly 
worked. 

3.  Fissure  veins  in  talcose  slate    and  gneiss,  and    filled  by  a 
quartz  gangue  with  bunches  of  malachite  and  azurite  (New  York 
and  Chicago  mines),  and  now  no  longer  worked. 

4.  Numerous   small   veinlets  forming  a    stockwork,   in    gneiss 
near  a  dike  of  diorite,  which  is  crossed  by  a  dike  of    trachyte. 
These  are  known  as  the  Black  Copper  Group.     The   ores  are  too 
low  grade  for  profitable  exploitation.     Of  greater  interest  are  the 
bodies  of  chrysocolla,  found  in  the  wash,  down  the  hill  from  the 
outcrop  of  the  veins,  and  evidently  due  to  the  superficial  drainage 
of  the  stockworks.     Similar  bodies  of  ore,  though  not  chrysocolla, 
were  found  at  Rio  Tinto,  in  Spain.2 

2.04.23.  Example  2Qd.    Santa  Rita  District.     Although  in  Xew 


1  J.  Douglass,  "Copper  Resources  of  the  United  States,"  M.  E.,  Sep- 
tember, 1890.    Rec.    A.  Wendt,  "  Copper  Ores  of  the  Southwest,"  M.  E., 
XV.,  p.  52.     Rec. 

2  J.  Douglass,  "Copper  Resources  of  the  United  States,"  M.  E.,  Sep- 
tember,  1890.      Rec.     "The  Globe  District,?'  Engineering  and  Mining 
Journal,  April  9, 1881,  p.  343.    W.  E.  Newberry,  "Notes  on  the  Produc- 
tion of  Copper  in  Arizona,"  School  of  Mines  Quarterly,  VI.  370.    A.  Trip- 
pel,  "  Occurrence  of  Gold  and  Silver  in  Oxidized  Copper  Ores  in  Arizona," 
Engineering  and  Mining  Journal,  June  16, 1883,  p.  435.    A.  Wendt,  "  Cop- 
per Ores  of  the  Southwest,"  M.  E.,  XV.,  p.  60. 


COPPER.  151 

Mexico,  this  district  has  much  in  common  with  those  already 
mentioned.  A  great  dike  of  felsite  cuts  limestones,  and  along  the 
contact,  as  well  as  in  the  felsite  itself,  copper  ores  are  found. 

1.  Contact  deposits  in  limestone.     These  afforded  the  usual  ox- 
idized ores,  but  were  not  found  to  extend  to  any  great  depth,  and 
while  for  a  time  productive,  they  were  soon  exhausted. 

2.  Deposits  in  felsite.     These  consisted  of  pellets  and  sheets  of 
native  copper  in  the  dike  itself,  which  were  oxidized  to  cuprite 
near  the  surface.     (Cf.  Lake  Superior  amygdaloids,  Example  13.) 
They  were  worked  by  the  Mexicans  in  the  early  part  of  the  pres- 
ent century.1 

2.04.24.  Example  20e.     Black  Range  District.     The  mines  of 
this  region  differ  from  those  described  above,  and  in  some  respects 
resemble  the  pyrite  beds  of  the  Alleghanies.     (Example  19.)     The 
ore  occurs  in  one  or  more  great  fissure  veins,  along  the  contact  of 
vertical  slates  with  a  great  dike  of  porphyrite.    The  veins  run  com- 
pletely into  the  porphyrite  and  into  the  slate,  and  afford  oxidized 
ores  above,  changing  into  chalcopyrite  below.     They  contain  con- 
siderable  silver  and  gold,  as  well  as  arsenic  and  antimony.     The 
principal  mines  are  the  Hampton  and  Eureka.     They  are  situated 
in  the  valley  of  the  Verde  River,  twenty  miles  east  of  Prescott.2 

2.04.25.  Example  20/.     Copper  Basin.     Beds  of  closely  text- 
ured conglomerate  and    sandstone,  resting  on  granite  and  gneiss, 
and  having  a  cement  of  copper  carbonates.     Copper  Basin   lies 
about  twenty  miles  southwest  of  Prescott,  and  is  formed  by  a  de- 
pression   in    greatly  decomposed  granite,    which  is  traversed    by 
numerous  small  veinlets  of  copper  ores.     The  granite  is  pierced  by 
porphyry  dikes,  and  covered  by   the  sedimentary   conglomerates 
and  sandstones  into  which  its  copper  is  thought  by  Blake  to  have 
partially   leached  and   precipitated  as  a  cement.     Reference,  by 
way  of  comparison,  may  be  made  to  the  Lake  Superior  conglomer- 
ates, in  which,  in  part,  the  native  copper  serves  as  a  cement.3 


1  A.  F.  Wendt,   "Copper  Ores  of  the  Southwest,"  M.  E.,  XV.  27. 
Wislizenus,  "On  the  Santa  Rita  Mines:  Memoir  of  a  Tour  in  Northern 
Mexico,  1846-47,"  p.  47 ;  Amer.  Jour.  Sci.,  ii.,  VI.  385,  1848. 

2  J.  F.  Blandy,  "The  Mining  Region  around  Prescott,  Ariz.,"  M.  E., 
XL  286.    G.  K.  Gilbert,  "On  the  General  Geology  of  the  Black  Mountain 
District,"  Wheeler's  Survey,  III.,  p.  35.    A.  R.  Marvine,  "  Brief  Details  of 
the  Verde  Valley,"  Wheeler's  Survey,  III.,  p.  209.    A.  F.  Wendt,  "  Copper 
Ores  of  the  Southwest,"  M.  E.,  XV.  63.     Rec. 

3  W.  P.  Blake,  V  The  Copper  Deposits  of  Copper  Basin,  Arizona,  and 
Their  Origin,"  M.  E.,  XVII.  479. 


152  KEMP'S   ORE  DEPOSITS. 

2.04.26.  There,  are  numerous  other  copper  districts  in  Arizona, 
of  minor  importance  or  entirely  undeveloped,  but  the  examples 
above  cited  probably  illustrate  the  occurrences  quite  fully.     Those 
not   referred    to    above    are    of   sporadic    development.     Mention 
should  also  be  made  of  the  mines  in  Lower  California,  opposite 
Guaymas,  a  brief  description  of  which  will  be  found  in  Wendt's 
paper.1 

2.04.27.  Example    20g.      Crismon-Mammoth,    Utah.      In    the 
Tintic  district,  Juab  County,  Utah,  are  three  great  ore  belts,  in 
vertically  dipping  dolomitic    limestone,   as   more   fully  set   forth 
under  "  Silver  "  (Example  35a).    One  of  these,  the  Crismon-Mam- 
moth, contains  ores  that  bear  silver,  gold,  and  copper  in  propor- 
tions of  about  equal   value.      They   have   been    a   very   difficult 
mixture  to  treat  successfully.      Of  late  considerable   copper  has 
been  produced,  placing  the  ore    deposits  among  those  deserving 
mention.     The  Crismon-Mammoth  vein  or   belt   covers   a   maxi- 
mum width  of  70  feet,  and  runs  500  feet  on  the  strike,  dipping  75° 
west.     The  ores  seem  to  have  been  deposited  along  the  bedding 
planes,  though  often  cutting  across   them.     The  productive  por- 
tions are  found  in  richer  chutes  or  chimneys,  amid  much  low-grade 
material  and  gangue,  and  are  of  all  shapes  and  sizes,  from  25  feet 
in  diameter,  down.    The  Copperopolis  is  thought  to  be  on  the  same 
belt,  and  is  a  neighboring  location  of  similar  geological  structure 
and  ores.2 

2.04.28.  Sunrise,  Wyoming.      Oxidixed    ores    have  been   ex- 
ploited to  some  extent  at  the  Sunrise  mines,  in  the  Laramie  range, 
Wyoming,  but  were  never  of  much  importance. 

2.04.29.  Example   21.      Copper  ores  in   Triassic   or    Permian 
sandstone.     They    occur    as    oxidized   ores,    native    silver,    and 
chalcocite  in  contact  deposits  in  Triassic  and  Permian  sandstones 
at  their  junction  with  diabase  or  gneiss,  or  as  disseminated  masses 
replacing    organic    remains.       Copper    ores    are    very    common 
throughout  the  estuary  Triassic  rocks  of  the  Atlantic  coast,  and 
although  formerly  much  mined,  they  are  now  proved  valueless,  and 
of  scientific  interest  only. 

2.04.30.  Example   21a.     Contact    deposits  in   sandstone  at  its 

1  See  also  M.  E.  Saladin,  "Note  sur  les  Mines  de  Cuivre  du  Boles 
(Basse  Californie),"  Bull,  de  la  Societe  de  Vlndustrie  Minerale,  3  Serie, 
VI.  5,  283. 

2  O.  J.  Hollister,  ''Gold  and  Silver  Mining  in  Utah,"  M.  E.,  XVI., 
p.  10.    D.  B.  Huntley,  Tenth  Census,  Vol.  XIII.,  p.  456. 


COPPER  153 

junction  with  diabase.  These  include  the  New  Jersey  ores,  vigor- 
ously worked  before  the  Revolution.  They  consist  of  the  carbon- 
ates, of  cuprite  and  native  copper,  disseminated  through  sand- 
stone near  the  trap.  The  Schuyler  mines,  near  Arlington,  N.  J., 
and  several  other  openings  near  New  Brunswick,  N.  J.,  are  best 
known.  These  Triassic  diabases  often  show  chalcopyrite,  and  it 
is  probable  that  the  copper  came  from  this  or  from  copper  in  the 
augite  of  the  rock,  in  accordance  with  Sandberger's  investigations. 
The  deposits  are  unreliable,  and  except  at  a  very  early  period 
have  never  been  an  important  source  of  ore. 

2.04.31.   Example  2lb.     Contact  deposits  in  sandstones  at  the 


FIG.  40. — Cross  section  of  the  Schuyler  Copper  mine,  New  Jersey,    a, 

trap;  b,  sandstone;  c,   shales;  the  black  shading,  copper  ores. 

After  N.  H.  Darton,  U.  S.  Geol.  Survey,  Bull  67,  p.  57. 

junction  with  gneiss.  A  number  of  deposits  were  formerly 
worked  of  this  character,  especially  at  Bristol,  Conn.,  and  at  the 
Perkiomen  mine,  Pennsylvania.  The  mine  at  Bristol,  Conn.,  is  a 
well-marked  contact  deposit,  on  the  line  between  the  Triassic 
sandstone  and  the  schistose  rocks.  The  contact  runs  northeast  and 
southwest,  has  suffered  great  decomjlbsition  from  mineral  solutions, 
and  has  been  largely  kaolinized.  A  broad  band  of  this  decomposed 
material,  30  to  120  feet  wide,  lies  next  the  sandstone  and  contains 
disseminated  ore.  Then  follow  micaceous  and  hornblende  slates, 
often  with  horses  of  gneiss.  The  slates  are  much  broken  by 
mpvements  that  have  formed  cavities  for  the  ores.  It  is  reason- 
able to  connect  the  stimulation  of  the  ore  currents  with  the 
neighboring  trap  outbreaks.  Unusually  fine  crystals  of  chalco- 


154  KEMP'S   ORE  DEPOSITS. 

cite  and  barite  have  made  the  mine  famous  the  world  over.  While 
at  one  time  a  source  of  copper,  for  many  years  it  has  been  unpro- 
ductive.1 

2.04.32.  Example  21c.  Chalcocite  and  copper  carbonates  re- 
placing vegetable  remains,  etc.,  in  the  Permian  or  Triassic  sand- 
stones of  Texas,  New  Mexico,  and  Utah.  In  the  Permian  of 
northern  central  Texas  are  three  separate  copper-bearing  zones, 
forming  three  lines  of  outcrop  that  extend  in  a  general  north- 
easterly direction  over  a  range  of  about  three  counties.  The  ore 
is  largely  chalcocite  in  beds  of  shale,  and  often  replacing  frag- 
ments of  wood.  It  may  be  available  in  time.2 

At  various  places  in  Utah  and  New  Mexico  (Abiquiu,  N.  M., 
Silver  Reef,  Utah)  the  sandstones,  as  reported  by  Newberry  and 
others,  have  copper  ores  disseminated  through  them  and  deposited 
on  fossils,  at  times  with  associated  silver  (Utah).  The  copper, 
whether  coming  from  the  waters  along  the  shore  line  or  from  sub- 
terranean currents,  was  precipitated  by  the  organic  matter.  (See 
also  under  "Silver,"  in  Utah.)  These  deposits  are  not  yet  sources 
of  copper.3 


1  L.  C.  Beck,  "  Notice  of  the  Native  Copper  Ores,  Copper,  etc.,  near 
New  Brunswick,  N.  J.,"  Amer.  Jour.  Sci.,  i.,  XXXVI.  107.  G.  H.  Cook,  Geol 
of  N.  J.,  1868,  p.  675;  also  L.  C.  Beck,  Ibid.,  218-224.    J.  G.  Percival,  Rep. 
on  Geol.  of  Conn.,  p.  77.    C.  A.  Shaeffer,  "Native  Silver  in  New  Jersey 
Copper  Ore,"  Engineering  and  Mining  Journal,  February,  1882,  p.  90.    C. 
Shepherd,  Geol.  of  Conn.,  1837,  p.  47.     B.  Silliman  and  J.  D.  Whitney, 
"Notice  of  the  Geological  Position  and  Character  of  the  Copper  Mine  at 
Bristol,  Conn.,"  Amer.  Jour.  Sci.,  ii.,  XX.  361.    J.  D.  Whitney,  Metallic 
Wealth.    Rec. 

2  W.  F.  Cummins,  "  Report  on  the  Permian  of  Texas  and  its  Over- 
lying Beds,"  First  Ann.  Rep.  Texas  Geol.  Survey,  p.  196.     J.  F.  Furman, 
"  Geology  of  the  Copper  Region  of  Northern  Texas  and  Indian  Territory," 
Trans.  N.  Y.  Acad.  Sci.,  1881-83,  p.  15. 

3  F.  M.  F.  Cazin,  "The  Origin  of  the  Copper  and  Silver  Ores  in  Tri- 
assic Sand  Rock,"  Engineering  and  Mining  Journal,  April  30,  1880  ;  Dec. 
11,  1880,  p.  331.     "The  Nacemiento  Copper  Deposits,"  Ibid.,  Aug.  22, 
1885,  p.  124.    A.   W.  Jackson,  Rep.  Director  of  the  Mint,  1880,  p.  334. 
J.  S.  Newberry,    "Copper  in  Utah,  Triassic  Sandstones,"  Engineering 
and  Mining  Journal,   Vol.  XXXI. ,   p.  5.      Also  Oct.  23,   1880,   p.   269; 
Jan.  1,  1881,  p.  4.    See  also  Tenth  Census,  Vol.  XIII.,  Precious  Metals, 
pp.  40,  478.     C.  M.  Rolker,   "The  Silver  Sandstone  District  of  Utah," 
M.  E.,  IX.  21.    R.  P.  Rothwell,  Quoted  in  Tenth  Census,  Vol.  XIII.,  p. 

-478.     B.  Silliman,  "  The  Mineral  Regions  of  Southern  New  Mexico,"  M.  E., 
XVI,  427. 


COPPER.  155 

2.04.33.  Copper  production  in  1882  and  1890,  in  tons  of  2000 
pounds  each. 

1883. 

Lake  Superior 28,578 

Montana 4,529 

Arizona 8,992 

Colorado 747 

New  Mexico 434 

California 413 

Utah 303 

Elsewhere 1,412 

45,408  129,546 

The  figures  indicate  in  general  a  vast  increase  in  production, 
and,  above  all,  the  advance  of  Montana.  For  detailed  statistics 
the  volume  on  "  Mineral  Industry  "  issued  by  the  Scientific  Pub- 
lishing Company  (New  York,  1893)  is  most  available. 


CHAPTER   Y. 

LEAD  ALONE. 

2.05.01.  The  deposits  of  lead  are  treated  in  three  different 
classes,  according  as  they  produce  or  have  produced  lead  alone, 
lead  and  zinc,  or  lead  and  silver.     Of  late  years  the  lead-silver  ores' 
have  been  the  great  source  of  the  metal.      Only  the    southeast 
Missouri  region  is  of  much  importance  among  the  others,  although 
considerable  lead  is  also  obtained  in  association  with  zinc. 

LEAD    SERIES. 

Pb.  S. 

Galena,  PbS 86.6  13.4 

Cerussite,  PbCO3 77.5 

Anglesite,  PbSO4 67.7 

Pyromorphite,  Pb3P3O8+l/3Pb.Cl2 75.36 

Earthy  mixtures  of  these  last  three  and  limonite. 

2.05.02.  Example  22.     Atlantic  border.     Veins  of  galena  in 
the  Archaean  rocks  of  the  States  along  the  Atlantic  border ;  also 
others  into  Paleozoic  strata,  as  described  in  the  sub-examples. 

2.05.03.  Example  22a.     Veins  in  gneiss  and  crystalline  lime- 
stone, sometimes  with  a  barite  or  calcite  gangue.     These  deposits 
were  vigorously  exploited  forty  years  ago  or  more,  but  have  since 
been  of  small  importance  other  than  scientific.      They  may   be 
described  best  by  districts,  as  they  hardly  deserve  a  greater  prom- 
inence. 

2.05.04.  (1)   St.   Lawrence  County,  New  York.     Veins  with 
galena  in  a  gangue  of  calcite  in    Archaean  gneiss.     Those  near 
Rossie  are  perhaps  best  known,  especially  for  their  unusually  in- 
teresting calcite  crystals.     There  are  numbers  of  veins  in  the  dis- 
trict which  are  notable  in  that  the  galena  is  without  zinc  or  iron 
associates.     The  lead  carries  a  very  small  amount  of  silver,  not 
enough  to  separate.     Hornblende  and  mica  schists  occur  in  the 
same  region  and  the  Potsdam  sandstone  is  not  far  removed.    A  few 


LEAD  ALONE.  157 

minor   veins   cut   the    Trenton    limestone   near    Lowville,    Lewis 
County,  sometimes  with  fluorite  for  a  gangue.1 

2.05.05.  (2)    Massachusetts,   Connecticut,    and    eastern    New 
York.     Veins  of  galena  with  more  or  less  chalcopyrite  and  pyrite 
in  a  quartz  gangue  in  gneiss,  slates,  limestones,  or  mica  schists. 
The  mines  near  Northampton,  Mass.,  were  formerly  well  known, 
although  never  productive  of  a  great  deal  of  metal ;  but  as  there 
is  a  large,  prominent  vein,  it  attracted  attention.     There  are  nu- 
merous others  in  the  same  region.     Veins  also  occur  at  Middle- 
town,  Conn.,  where  much  silver  is  said  to  be  found  in  the  galena. 
More  recently  (circa  1873)  at  Newburyport,  Mass.,  argentiferous 
galena  attracted  attention,  but  was  not  of  any  importance.    Other 
veins  are  known  in  Lubeck,   Me.,   and  in  various  parts  of  New 
Hampshire  and  Vermont.     For  a  time  small  lodes  in  the  slates  of 
Columbia   County,  New  York,    were  unsuccessfully  exploited,  of 
which  the  Ancram  mine  is  of  historic  interest.     Although  these 
galena  veins  are  numerous,  they  are  not  to  be  taken   too   seri- 
ously.2 

2.05.06.  (3)  Southeastern    Pennsylvania.     Veins  on    the  con- 
tact of  Archaean  gneiss  and  Triassic  sandstone  and  diabase.    These 
were  referred  to  under  Example  2lb.     As  noted  by  Whitney,  the 
copper  is  especially  strong  in  the  sandstone,  and  the  lead  in  the 
gneiss.     Trap  dikes  are  abundant,  and  the  eruptive  phenomena  in 
connection  with  them  doubtless  occasioned  the  activity  of  circula- 
tion which  filled  the  veins.     The  Wheatley  mine  is  best  known. 
It  has  afforded  a  great  variety  of  lead  minerals,  especially  pyro- 
morphite.     They  have  not  been  worked  in  years.3 

2.05.07.  (4)     Davison  County,  North  Carolina.     Veins  in  tal- 
cose    slate  were   formerly  exploited,   but    are  now  little   known, 


1  L.  C.  Beck,  Mineralogy  of  New  York,  p.  45.     E.  Emmons,  "  Geology 
of  the  Second  District,"  N.  Y.  Geol.  Survey,  1842.     G.  Hadley,  "Crystal- 
lized Carbonate  of  Lead  at  Rcssie,"  Amer.  Jour.  Sci.,i\.,  II.  117.     F.  L.  Na- 
son,  "  Calcite  from  Rossie,"  Bull  4,   N.  Y.   State  Museum,   1888.     J.  D. 
Whitney,  Metallic  Wealth.    Rec. 

2  C.  A.  Lee,  "Notice  of  the  Ancram  Lead  Mine,"  Amer.  Jour.  Sci., 
i.,  VIII.  247.     A.  Nash.  "  Notice  of  the  Lead  Mines  and  Veins  in  Hampshire 
County,  Massachusetts,"  Amer.  Jour.  Sci.,  i.,  XII.  238.     R.  H.  Richards, 
"The  Newburyport  Silver  Mines,"  M.  E.,  III.  442.     J.  D.  Whitney,  Me- 
tallic Wealth. 

8  H.  D.  Rogers,   Geol.  of  Penn.,  II.  701  ;  also  Amer.  Jour.  Sci.,  ii., 
XVI.  422.     J.  D.  Whitney,  Metallic  Wealth,  p.  396. 


158  KEMP'S   ORE  DEPOSITS. 

except  as  having  furnished    beautiful    crystals    of   oxidized  lead 
minerals.1 

2.05.08.  Example    22b.     Sullivan    and   Ulster  Counties,  New 
York.     Veins  along  a  line  of  displacement  on  the  contact  between 
the  Hudson  River  slates  and  the  sandstones  of  the  Medina  stage 
(Shawangunk  grit),  carrying  galena  and  chalcopyrite  in  a  quartz 
gangue  ;  or  else  gash  veins  filled  with  the  same  in  the  grit.    These 
mines  formerly  produced  considerable  lead  and  copper,  but  are 
now  best  known  for  the  excellent  quartz  crystals  which  they  have 
furnished  to  all  the  mineralogical  collections   of  this   and   other 
lands.2 

2.05.09.  Example    23.     Southeast  Missouri.     Galena    accom 
panied  by  nickeliferous  pyrite,  disseminated  through  beds  of  the 
Third  or  Lower  Magnesian  limestone  of  the  Missouri  geologists, 
which  is  doubtless  Cambrian  in  age.     The  mines  are  at  Bonne 
Terre,  Mine  La  Motte,  and  Doe  Run,  twenty-five  miles  west  of  the 
Mississippi  River  and  forty  to  one  hundred  miles  south  of  St.  Louis. 
The  strata  lie  almost  horizontal,   and  are  known  to  carry  lead 
through  over  200  feet  in  thickness.     The  productive  places  fade 
out  into  barren  rock  and   appear  to  be  local  enrichments  of  the 
limestone,  of  which  the  galena  forms  an  integral  part.     At  Bonne 
Terre  they  are  of  enormous  size,  one  working  running  3000  feet,  and 
being  100  to  200  feet  broad  and  25  to  60  feet  high.    No  zinc,  how- 
ever, occurs  with  the  lead,  and  the  silver  contents  are  very  small, 
being  about  four  ounces  to  the  ton  of  lead.     At  Mine  La  Motte 
some  copper  is  found,  and  considerable  nickel  and  cobalt.     The 
rare  mineral  siegenite,  a  variety  of  linnaeite,  impregnates  a  sand- 
stone supposed  to  be  the  equivalent  of  the  Potsdam.  Pyrite  accom- 
panies the  galena  both  at  Mine  La  Motte  and  at  the  other  mines,  and 
carries  the  nickel  and  cobalt,  which  is  obtained  as  a  by-product  in  the 
lead  smelting.     All  the  ore  bodies  are  crossed  by  small  faults,  ad- 
joining which  the  rock  is  invariably  barren.     Knobs  of  Archaean 
granite,  containing  diabase  dikes,  crop  out  near  the  mines  both  at 
Mine  La  Motte  and  at  Doe  Run.     But  the  dikes  never  penetrate 
the  limestone,  and  were  evidently  intruded  before  it  was  deposited. 


1  J.  C.  Booth,  "  Analyses  of  Various  Ores  of  Lead,  etc.,  from  King's 
Mine,  Davison  County,  North  Carolina."  Amer.  Jour.  Sci.,  i.,  XLI.  348.    W. 
C.  Kerr,  Geol  of  North  Carolina,  p.  289. 

2  J.  D.  Whitney,  Metallic  Wealth.    W.  W.  Mather,  New   York  State 
Survey,  Report  on  First  District,  358. 


LEAD  ALONE.  159 

The  ore  must  have  been  deposited  with  the  limestone  or  it  must 
have  been  introduced  since  the  latter  was  formed,  and  by  the  per- 
colation of  ore-bearing  solutions  through  the  rock,  with  no  marked 
fissure  vein  development.  The  first  view  has  been  advanced  by  J. 
F.  Kemp  (1887),  it  being  thought  that  decaying  marine  vegetation 
had  precipitated  the  ores  from  solution  in  sea-water,  as  is  outlined 
for  another  region  under  Example  24,  but  this  explanation  has 
been  practically  disproved.  W.  P.  Jenney  has  considered  the  ore 
to  have  come  in  ascending  solutions  through  the  small  fault  fis- 
sures referred  to  above,  and  from  these  to  have  spread  outward,, 
replacing  the  limestone  (privately  communicated).  Places  where 
several  fissures  cross  are  said  to  be  specially  favorable.  It  is  a 
curious  fact,  however,  that  as  the  ore  bodies  are  followed  up  to  the 
faults  they  invariably  become  lean  or  run  out.  Their  place  of 
formation  has  apparently  some  connection,  as  recent  explorations 
seem  to  indicate,  with  low  folds  at  right  angles  to  the  faults.  The 
ore  bodies  favor  the  anticlinal  bends. 

This  whole  region  of  Cambrian  and  Lower  Silurian  rocks,  over 
nearly  3000  square  miles,  contains  lead,  and  within  a  year  or  so  past 
some  new  mines,  not  yet  under  way  (1892),  have  been  started. 
These  disseminated  deposits  are  in  no  way  to  be  confused  with 
the  mines  of  the  Upper  Mississippi  in  Wisconsin  and  Iowa.  They 
are  now  large  producers  of  lead  and  the  only  mines  worked  in  the 
United  States  for  lead  alone.  The  ore  affords  an  average  of  about 
eight  per  cent,  galena.  Except  at  Mine  La  Motte,  lead  was  also 
obtained  at  this  region,  previously  to  1865,  from  small  gash  veins 
like  those  of  Example  24,  but  the  workings  were  never  in  any  de- 
gree commensurate  with  the  present  mines  of  disseminated  ore. 
The  history  of  Mine  La  Motte  dates  back  to  the  early  part  of  the 
eighteenth  century,  and'it  is  said  to  have  furnished  lead  for  bullets 
used  in  the  Revolution.1 

2.05.10.  The  great  increase  in  lead  production  in  the  United 
States  came  about  1880,  with  the  opening  of  the  Leadville  ore 

1  G.  C.  Broadhead,  "  The  Southeastern  Missouri  Lead  District,"  M.  E., 
V.  100.  Rec.  J.  R.  Gage,  "  On  the  Occurrence  of  Lead  Ores  in  Missouri," 
M.  E.,  III.  116.  Rec.  Oeol.  •  Survey  of  Missouri,  1873-74,  pp.  30,  603.  J. 
F.  Kemp,  "Notes  on  the  Ore  Deposits,  etc.,  in  Southeastern  Missouri," 
School  of  Mines  Quarterly,  October,  1887.  Rec. 

Several  other  papers  have  been  published  on  the  metallurgical  treat- 
ment and  methods  of  ore  dressing  in  the  Trans.  Inst.  of  Mining  Engineers 
and  the  School  of  Mines  Quarterly. 


160  KEMP'S   ORE  DEPOSITS. 

bodies.  From  1877  until  1881  Eureka,  Nev.,  was  an  important 
source,  but  since  then  it  has  greatly  declined.  Utah  has  preserved 
a  fairly  uniform  production  since  the  early  seventies.  Lead  from 
all  sources  is  here  mentioned,  although  lead-silver  ores  are  sub- 
sequently treated.  The  amounts  are  in  tons  of  2000  pounds.  For 
detailed  statistics  see  the  volume  on  "  Mineral  Industry."  (New 
York  :  Scientific  Publishing  Company,  1893.) 

1880.  1890. 

Missouri,  Kansas,  Wisconsin,  Illinois 27,690  55,000 

Colorado 35,674  60,000  • 

Nevada 16,659  2,500 

Utah 15,000  24,000 

Idaho,  Montana 24:000 

Elsewhere 2,802  15,994 


97,825  181,494 

From  80  to  85$  of  the  total  product  is  from  lead-silver  ores. 


CHAPTER     VI. 

LEAD  AND   ZINC. 

2.06.01.  Example  24.   '  The  Upper  Mississippi  Valley.     Gash 
veins  and  horizontal   cavities  (flats),  limited  to  the  Galena   and 
Trenton  limestones  of  the  Upper  Mississippi  Valley,  and  contain- 
ing galena,   zincblende,  and   pyrite  (or  marcasite),  with   calcite, 
barite,  and  residual  clay.     The  deposits  are  found  in  southwest 
Wisconsin,  eastern  Iowa,  and  northwestern  Illinois.     The  greater 
portion  of  the  productive  territory  lies  in  Wisconsin,  and  covers 
an  area  which  would  be  included  in  a  circle  of  sixty  miles'  radius, 
whose  limits  would  pass  a  few  miles  into  Illinois  and  Iowa.  A  low 
north  and  south  geanticline  runs  through  central  Wisconsin  dat- 
ing back  to  Archaean  times  and  called  by  Chamberlain  "Wisconsin 
Island."     On  its  western  slope  the  Cambrian  and  Lower  Silurian 
rocks  are  laid  down,  and  these  in  the  western  limit  of  the  lead  dis- 
trict pass  in  the  adjoining  States  under  the  Upper  Silurian.    They 
are  folded   also  in  low  east  and  west  folds,  but  in   the   aggregate 
the  whole   series   dips  very  gradually  westward.     The   chief  east 
and  west  fold  forms  the  south  bank  of  the  Wisconsin  River,  and 
may  have   been   the   cause   that   deflected   it   from   a   southerly 
course.     The  easterly  part  of  the  lead  region  is  350   feet  higher 
than  the  western,  and  the  northern  is  500  feet  above  the  southern. 
The  general  slope  is  thus  southwesterly. 

2.06.02.  The  Galena  limestone  is  a  dolomite  reaching  250  feet 
in  thickness.     .On  the  hilltops  left  by  erosion  Maquekota  (Hudson 
River)  shales  are  seen.      The  Galena  has  shaly  streaks,  which  have 
largely  furnished  the  residual  clay  of  the  cavities.     There  are  also 
cherty  layers  and  sandy  spots.     Under  the  Galena  lies  the  Tren- 
ton, from  40  to  100  feet  thick,  and  made  up  of  an  upper  blue  por- 
tion, which  is  a  pure  carbonate  of  lime,  and  a  lower  buff  portion 
that  is  magnesian.     The  upper  portion  of  the  blue  has  a  band  of 
shale  locally  called  the  "  Upper  Pipe  Clay,"  and  the  pure,  crypto- 
crvstalline  limestone  under  this  is  called  "  Glass  Rock."    The  blue 


162 


KEMP'S    ORE  DEPOSITS. 


contains  much  bituminous  matter.  The  buff  is  locally  called 
"  Quarry  Rock  "  and  is  prolific  in  fossils.  Under  the  Trenton  lies 
the  St.  Peter's  sandstone,  150  feet  below  which  is  the  Lower  Mag- 
nesian,  100  to  250  feet,  and  still  lower  the  Potsdam,  averaging 
700  to  800  feet.  The  Potsdam  rests  on  the  quartzites  and  schists 
of  the  Archaean.  The  ore  beds  especially  favor  the  shallow,  syn- 
clinal depressions  of  the  east  and  west  folds.  They  occur  in  crev- 
ices, the  great  majority  of  which  run  east  and  west.  The  pro- 
ductive ground  comes  in  spots  which  are  separated  by  stretches. 


FIG.  41. — Gash  veins,  fresh  and  disintegrated.     The  heavy  black  shading 
indicates  galena.    After  T.  C.  Chamberlain,  Oeol.  Wis. ,  Vol.  IV.,  p.  454. 

of  barren  ground.  The  lead  ores  are  chiefly  produced  by  the 
crevices  in  the  Upper  Galena.  In  the  Lower  Galena  the  zinc  ores 
become  relatively  more  abundant,  and  they  are  also  in  the  Tren- 
ton. The  ores  do  not  extend  in  any  appreciable  amounts  either 
above  or  below  these  horizons.  The  upper  deposits  favor  the  ver- 
tical gash  vein  form ;  the  lower  tend  rather  to  horizontal  open- 
ings, called  flats,  which  at  the  ends  dip  down  (pitches)  and  often 
connect  with  a  second  sheet  (flat)  lying  lower.  There  are  several 
minor  varieties  of  those  two  main  types  of  cavity,  which  mainly 
depend  for  their  differences  on  the  grade  of  decomposition,  which 
the  walls  have  undergone,  and  whether  there  was  an  original  open- 


LEAD  AND  ZINC. 


163 


ing,  or  only  a  brecciated  and  crushed  strip.  Chamberlain  cites 
twelve  varieties  in  all,  some  of  which  are  based  on  rather  fine  dis- 
tinctions. 

2.06.03.  The  cavities  were  referred  by  J.  D.  Whitney  to 
joints,  formed  either  by  the  drying  and  consolidating  of  the  rock 
or  by  gentle  oscillations  of  the  inclosing  beds.  The  later  work 
lias  largely  corroborated  this,  and  they  are  generally  thought  to 
be  chiefly  caused  by  the  cracks  and  partings  formed  by  the  gentle 
synclinal  foldings.  Such  cavities  have  usually  been  enlarged  by 
subsequent  alteration  of  the  walls.  Whitney  also  essentially  out- 
lined the  explanation  of  origin,  which  has  been  more  fully  elabo- 


_^__  v  ^ 

—  *£  C±;fiu^ 

n  —   Galena          ' 

—    time^  Stone    ,^.^ 

FIG.  42.  —  Idealized  section  of  "flats  and  pitches,"  forms  of  ore  bodies  in 
Wisconsin.    After  T.  C.  Chamberlain,  Geol.  Wis.,  Vol.  IV.,  p.  458. 

rated  by  Chamberlain.  Both  these  writers  have  urged  that  the 
ores  could  not  have  come  from  below,  for  the  lower  rocks  are  sub- 
stantially barren  of  them.  The  conclusion  therefore  follows  that 
they  were  deposited  in  the  limestones  at  the  time  of  their  forma- 
tion. The  source  of  the  ores  is  placed  in  the  early  Silurian  sea, 
from  which  it  is  thought  they  were  precipitated  by  sulphuretted 
hydrogen,  exhaled  by  decaying  seaweeds,  or  similar  dead  organ- 
isms on  the  bottom.  In  carrying  the  idea  further,  Chamberlain 
has  endeavored  to  reproduce  the  topography  of  the  region  in  the 
Lower  Silurian  times  and  to  indicate  the  probable  oceanic  cur- 
rents. These  are  conceived  to  have  made  an  eddy  in  the  lead 
district  and  to  have  collected  there  masses  of  seaweed,  etc.,  re- 
sembling the  Sargasso  Sea.  While  interesting,  this  must  be  con- 
sidered very  hypothetical.  When  the  sulphides  became  precipi- 


164  KEMP'S  ORE  DEPOSITS. 

tated  they  were  doubtless  finely  disseminated  in  the  rock  and 
were  gradually  segregated  in  the  crevices.  The  sulphurous  exhala- 
tions from  the  bituminous  limestones  may  have  aided  in  their 
second  precipitation.  The  paragenesis  of  the  minerals  shows  the 
following  succession  :  (1)  Pyrite,  (2)  Galena,  (3)  Pyrite;  or  (1) 
Pyrite,  (2)  Blende,  (3)  Galena,  (4)  Pyrite;  or  (4)  Calcite.  The 
ores,  especially  of  zinc,  are  often  oxidized,  and  afford  considerable 
calamine  and  smithsonite.  Some  oxidized  copper  ores  are  pro- 
duced at  Mineral  Point,  formed  by  the  alteration  of  chalcopyrite. 
In  the  early  mines  lead  alone  was  sought,  but  of  late  years  the 
zinc  has  been  produced  in  greater  quantities  and  is  more  valuable 
than  the  lead. 

Dr.  W.  P.  Jenney,  whose  work  in  the  region  of  southwest  Mis- 
souri is  later  referred  to  (2.06.07),  has  also  written  of  these  mines, 
and  his  views  are  quite  different  from  those  of  any  of  the  writers 
mentioned  above.  The  courteous  permission  to  read  his  manu- 
script has  made  possible  the  following  abstract.  The  east  and 
west  fissures,  already  mentioned  as  crevices,  are  regarded  as  faulting 
planes.  They  are  usually  not  far  from  the  vertical,  but  in  a  few 
instances  dip  35°  to  45°.  The  smaller  north  and  south  series  are 
considered  to  be  due  to  the  same  cause,  but  to  an  earlier  period  of 
disturbance,  as  they  are  faulted  by  the  east  and  west  set.  The 
latter  exhibit  but  little  vertical  displacement,  although  some  con- 
siderable horizontal.  The  ore  is  principally  in  and  along  the  east 
and  west  fissures,  but  these  seem  to  be  locally  enriched  at  their 
intersections  with  the  north  and  south  series.  The  deposits  are 
described  as  runs  ;  that  is,  lateral  enrichments  along  a  fissure. 
The  ores  are  thought  to  have  come  up  from  below  through  the 
chief  fissures,  and  in  this  respect  Dr.  Jenney's  views  radically 
differ  from  those  of  the  earlier  writers.  The  solutions  are  said  to 
have  favored  particular  beds  for  the  following  reasons.  The  beds 
were  cellular  from  long  exposure  to  atmospheric  agents,  or  they 
were  chemically  (being  dolomitic)  and  physically  of  a  nature  to 
occasion  it,  or  they  were  soft  and  permeable  shaly  beds.i  (See 
also  under  2.06.07.) 

1  WISCONSIN. 

J.  A.  Allen,  "Description of  Fossil  Bones  of  Wolf  and  Deer  from  Lead 
Veins,"  Amer.  Jour.  Sri.,  iii.,  II.  47.  T.  C.  Chamberlain,  Wis.  Geol  Sur- 
vey, Vol.  IV.,  1882,  p.  367.  Rec.  E.  Daniels,  "  Geology  of  the  Lead  Mines 
of  Wisconsin,"  A.  A.  A.  S.,  VII.  290;  Engineering  and  Mining  Journal, 
July  6,  13,  20,  27,  Aug.  3,  10,  24,  Oct.  5,  1878 ;  Wis.  Geol.  Survey,  1854. 


LEAD  AND  ZINC.  165 

2.06.04.  Example  24a.     Washington  County,  Missouri.     Gash 
veins  in   the  Lower  Magnesian  limestones  of  eastern  Missouri  in 
the  same  region  as  the  disseminated  ores  of  Example  23,  and  con- 
taining galena,  barite   (locally  called  "tiff"),  calcite,  and  residual 
clay.     The  cavities  are  described  by  Whitney  as  resembling  in  all 
respects  the  gash  veins  farther  north,  which,  however,  lie  in  rocks 
higher  in   the  geological  series.     These  mines  were  the  earliest 
worked,  but  have  been  given  up  since  the  price  of  lead  has  been 
at  present  figures  (1875  and  subsequently).     The  ore  was  obtained 
from  pockets,    caves,   irregular  cavities,  and  from  the  overlying 
residual  clays.     This  whole  region  has  been  exposed   and  above 
water  since  the   close  of    Carboniferous  times  and   has    suffered 
enormous  surface  decay  (see  R.  Pumpelly,    Tenth    Census,  VoL 
XV.,  p.  12,  and  Geol.  Soc.  Amer.,  Vol.  II.,  p.  20),  which  has  left  a 
mantle  of  residual  clay  spread  widely  over  its   extent.    In  this, 
more  or  less  float  mineral  occurred.     The  mines   were  located  in 
Washington,  Franklin,  Jefferson,  and  St.  Frangois  counties.1 

2.06.05.  Example  24b.     Livingston  County,  Kentucky.    Veins 
in   limestone  of  the  St.  Louis  stage  of  the  Lower  Carboniferous, 
containing  galena  in  a  gangue  of  fluorite,  calcite,  and  clay.     The 


James  Hall,  "Notes  on  the  Geology  of  the  Western  States,"  Amer.  Jour. 
Sci.,  i.,  XLII.  51.  J.  T.  Hodge,  "  On  the  Wisconsin  and  Missouri  Lead  Re- 
gion," Amer.  Jour.  Sci.,  i.,  XLIII.  35.  R.  D.  Irving,  "Mineral  Resources 
of  Wisconsin,"  M.  E.,  VIII.  478.  E.  James,  "  Remarks  on  the  Limestones 
of  the  Mississippi  Valley  Lead  Mines,"  Phil.  Acad.  Sci.,  V.,  Part  I.,  p.  51. 
J.  Murrish,  Report  on  the  lead  regions,  1871,  as  commissioner  for  their 
survey.  D.  D.  Owen,  "Report  on  the  Lead  Region,"  U.  S.  Senate  Docu- 
ments, 1844.  J.  G.  Percival,  Wis.  Geol.  Survey,  1856.  Squier  and  Davis, 
Historical  account,  Smithsonian  Contributions,  Vol.  I.,  p.  208.  M.  Strong, 
Wis.  Geol.  Survey,  1877,  I.  637;" II.  645,  689.  J,  D.  Whitney,  Wis.  Geol. 
Survey,  1861-62, 1.  221.  Rec.  Metallic  Wealth,  p.  403,  1856.  "  On  the  Oc- 
currence of  Bones  and  Teeth  in  the  Lead-bearing  Crevices,"  A.  A.  A.  S., 
1859. 

ILLINOIS. 

J.  Shaw,  Geol.  Survey  of  Illinois,  1873,  Vol.  II.,  p.  340.  J.  D.  Whit- 
ney, Geol.  Survey  of  Illinois,  1866,  Vol.  I.  153. 

IOWA. 

C.  A.  White,  Iowa  Geol.  Survey,  1870,  Vol.  II.,  p.  339.  J.  D.  Whit- 
ney, Iowa  Geol.  Survey,  1858,  Vol.  L,  p.  422. 

1  Compare  the  older  references  under  Example  23,  and  the  following: 
A.  Litton,  Second  Ann.  Rep.  Missouri  Geol.  Survey,  1854.  J.  D.  Whitney, 
Metallic  Wealth,  p.  419. 


166  KEMP'S   ORE  DEPOSITS. 

ore  bodies  have  never  been  well  described  and  no  very  accurate 
diagnosis  can  be  given.  They  are  found  in  Livingston,  Crittenden, 
and  Caldwell  counties,  Kentucky,  in  that  portion  of  the  State 
lying  south  of  the  Ohio  River  and  east  of  the  Cumberland.  "While 
limestone  always  forms  one  wall,  a  sandstone  of  geological  rela- 
tions not  well  determined  forms  the  other.  The  veins  run  from 
two  to  seven  feet  wide  and  in  instances  are  richer  in  their  upper 
portions  than  in  the  lower.  As  yet  they  are  of  greater  scientific 
than  practical  importance.  Some  galena  occurs  also  in  irregular 
cracks  in  the  limestone.  As  a  possible  indication  of  a  stimulating 
cause  for  the  formation  of  the  veins,  the  interesting  dike  of  mica- 
peridotite  may  be  cited,  which  has  been  described  by  J.  S.  Diller.1 
The  dike  occurs  in  the  same  fissure  with  a  vein  of  fluorspar.2 

2.06.06.  Example  25.  Southwest  Missouri.  Zincblende  and 
very  subordinate  galena  with  their  oxidized  products,  associated 
with  chert,  residual  clay,  calcite,  a  little  pyrite  and  bitumen,  in 
cavities  of  irregular  shape  and  in  shattered  portions  of  Subcarbon- 
iferous  limestone.  Across  Missouri,  from  a  point  south  of  St. 
Louis,  and  including  the  country  as  far  to  the  northwest  as 
Sedalia  and  Glasgow,  a  broad  belt,  called  the  Ozark  uplift,  extends 
southwesterly  into  Arkansas.  It  has  formed  a  great  plateau  in 
central  and  southern  Missouri  and  consists  largely  of  Silurian 
rocks.  These  have  a  fringe  of  Devonian  on  the  edges  and  dip  un- 
der the  Lower  Carboniferous.  The  plateau  reaches  1500  feet  above 
the  sea  in  Wright  County,  but  on  the  limit  is  succeeded  by  lower 
country.  To  the  southwest  it  drops  somewhat,  with  Lower  Car- 
boniferous strata  outcropping,  which  in  Kansas  are  overlain  by  the 
coal  measures.  The  surface  then  rises  again  in  the  prairies.  At 
the  edge  of  the  plateau  is  a  trough,  in  whose  bottom  the  Lower 
Carboniferous  strata  are  cut  by  the  Spring  River,  which  flows 
southwesterly  from  Missouri  across  the  western  State  line  into 
Kansas  and  has  a  general  direction  parallel  to  the  western  limits 
of  the  uplift.  It  receives  tributary  streams  on  each  bank,  which 
cut  the  strata  in  strongly  marked  valleys  and  afford  good  ex- 
posures. Those  on  the  east  bank,  from  south  to  north,  are  Shoal 


1  "  Mica-Peridot ite  from  Kentucky,"  Amer.  Jour.  Sti.,  October,  1892. 

2  S.  F.  Emmons,  "Fluorspar  Deposits  of  Southern  Illinois,"  M.  E., 
February,  1892.    C.  J.  Norwood,  "  Report  on  the  Lead  Region  of  Living- 
ston, Crittenden,  and  Caldwell  Counties,"  Kentucky  Geol.  Survey,  1875, 
New  Series,  Vol.  I.,  p.  449. 


LEAD  AND  ZINC.  16? 

Creek,  Short  Creek,  Turkey  Creek,  and  Center  Creek,  while  from 
the  west  come  the  Brush,  Shawnee,  and  Cow  creeks,  all  in  Kansas. 
Along  the  first  mentioned  creeks  the  principal  mining  towns  are 
situated,  but  others  are  found  on  the  minor  streams.  They  extend 
through  an  area  fifteen  miles  broad  from  east  to  west  and  twenty- 
five  miles  from  north  to  south.  Newton  and  Jasper  aTe  the  most 
productive  counties  in  Missouri,  while  Cherokee  County,  in  Kansas, 
also  contains  notable  mines.  Undeveloped  districts  are  recorded  in 
Arkansas,  but  apparently  at  a  lower  geological  horizon.  The  ore 
occurs  in  the  Keokuk  or  Archimedes  limestone  of  the  Lower  Car- 
boniferous. A  generalized  section  of  the  rocks,  according  to  F.  L. 
Clerc,  is  as  follows.  On  the  higher  prairie,  some  15  feet  of 
clay  or  gravel ;  10  feet  of  flint  or  chert  beds  ;  40  *feet  of  lime- 
stone with  thin  beds  of  chert ;  60  feet  of  alternating  layers  of 
limestone  and  chert;  100  feet  and  more  of  chert,  sometimes  chalky 
with  occasional  beds  of  limestone ;  225  feet  in  total.  In  basins 
and  extensive  pockets  in  these  rocks,  deposits  of  slates  with  small 
coal  seams  are  found,  of  undetermined  geological  relations.  The 
large  bed  of  limestone  of  the  section  affords  a  datum  of  reference 
in  relation  to  which  the  ores  may  be  described.  A  few  minor, 
shallow  deposits  occur  in  the  flints  over  it.  In  the  limestone  the 
ores  are  associated  with  a  gangue  of  dolomitic  clay  and  residual 
flint.  They  occupy  irregular  cavities  or  openings,  locally  known 
as  circles,  spar  openings,  and  runs.  (Clerc.)  Below  the  limestone 
the  ore  is  found  in  "  sheets,  bands,  seams,  and  pockets,"  and  filling  in 
the  interstices  of  a  breccia  of  chert,  which  has  been  formed  by  the 
breaking  down  of  the  chert  layers  on  the  solution  and  removal  of 
the  interbedded  limestones.  There  are  districts  where  the  over- 
lying bed  of  limestone  has  also  disappeared,  and  they  then  lack 
it  for  a  capping.  The  deposits  extend  to  considerable  depths  be- 
low the  position  of  the  limestone.  The  present  mines  have  not 
demonstrated  as  yet  their  limit  of  depth.  At  times  the  ore  is 
associated  with  a  later  formed  quartz  rock  that  has  coated  and 
filled  the  cavities  of  the  breccia. 

2.06.07.  The  removal  of  the  interbedded  layers  of  limestone 
and  the  caving  in  of  the  associated  cherts  have  been  the  principal 
causes  of  the  formation  of  cavities.  Adolph  Schmidt  referred  the 
shrinkage  to  the  dolomitization  of  pure  lime  carbonate,  an  idea 
that  has  had  extended  adoption,  and  has  also  had  an  important 
part  in  causing  the  general  porosity.  Schmidt  traced  five  periods 
in  the  geological  history  of  the  ore  bodies:  1.  Period  of  deposition 


168 


KEMP'S   ORE  DEPOSITS. 


of  the  rocks.  2.  Period  of  dolomitization  of  certain  strata  and  of 
principal  ore  deposition.  3.  Period  of  dissolution  of  part  of  the 
limestone,  of  breaking  down  of  chert,  and  of  continued  but  di- 
minishing ore  deposition.  4.  Period  of  regeneration,  secondary 
deposition  of  carbonate  of  lime  and  quartz,  and  continued  ore  de- 
position. 5.  Period  of  oxidation. 

Schmidt's  work  was  done  in  1871-72.    Since  then  the  increased 


___   tuminoua 
slate  &  coal 


x  /   .  ,  ,    ..  /  /    .    .-  /  /  /  \>  .    ,•     •    .    .-   ,•  .',•/,-.'   f  /  /  /'/    ,-  /  •'  Probable  flint  floor  of 
• f*i -J  v'v'^'^V  v'  N/V'V'V/ <.'*.'  -J  \S  v'v'  v'v'^'v/v'' v' v  \/x.'v.'v.' io'v'*'          ore-deposit. 
TYPICAL  ZINC-BLENDE  ORE^BODY  NEAR  WEBB  CITY,  Mo.   VERTICAL  SECTION, 
ifarous  Limestone 

^W^fcZmc.blende  ore-bodiea 


Galenite  in  fissures  &  bedding-planes  in  limestone 

FIG.  43.— Vertical  section  of  a  typical  zincblende  ore  body,  near  Webb 
City,  Mo.    After  C.  Henrich,  M.  E.,  June,  1892. 

development  of  .the  mines  has  afforded  greater  opportunities  for 
observation.  Haworth,  in  1884,  referred,  with  much  reason,  the 
shattering  of  the  chert  in  certain  areas  to  oscillations  of  the  strata, 
and  Clerc,  in  1887,  emphasized  particularly  the  dissolving  action  of 
water.  A  forthcoming  description  by  W.  P.  Jenney,  of  the  United 
States  Geological  Survey,  is  awaited  with  great  interest.  While 
the  formation  of  the  cavities  and  the  method  of  introduction  of 
the  ore  are  not  so  difficult  to  understand,  it  is  a  hard  problem  to 
discover  the  original  source  of  the  metals.  No  published  account 


I 

! 

I 

sT 

•I 


170  KEMP'S  ORE  DEPOSITS. 

brings  them  up  from  below.  Haworth  discusses  a  possible  pre- 
cipitation from  the  ocean,  as  is  outlined  under  Example  24,  and 
Clerc  mentions  the  pockets  of  slate  and  coal  as  a  probable  source. 
Further  and  more  extended  study  of  the  mines  has  been  much 
needed. 

A  brief  outline  of  Dr.  Janney's  views  is  here  given,  which  has 
been  abstracted  from  manuscript  that  he  has  kindly  allowed  the 
writer  to  see  in  advance  of  its  publication.  In  the  forthcoming 
report  all  the  lead  or  lead  arid  zinc  regions  of  the  Mississippi 
Valley  are  considered  together.  They  are  described  as  occurring 
along  three  lines  of  upheaval.  The  region  of  Wisconsin  and  Iowa 
is  on  the  flanks  of  the  Archaean  "  Wisconsin  Island  "  of  Chamber- 
lain, referred  to  above  under  2.06.01.  The  southeast  and  southwest 
Missouri  regions  are  on  the  Ozark  uplift,  while  a  minor  argentif- 
erous galena  district  is  on  the  line  of  the  Ouachita  uplift  of  Ar- 
kansas and  Indian  Territory.  The  formation  of  the  ore  bodies  in 
the  first  three  of  these  is  regarded  as  having  been  in  general  the 
same.  They  are  thought  to  have  originated  from  uprising  solu- 
tions, which  came  through  certain  principal  fissures,  and  spread 
laterally  into  strata  favorable  to  precipitation.  In  southwest  Mis- 
souri this  was  the  Cherokee  limestone  of  the  Lower  Carboniferous. 
In  its  unaltered  state  it  is  an  extremely  pure  carbonate  of  lime.  It 
has  a  maximum  thickness,  where  not  eroded,  of  165  to  200  feet, 
and  contains  many  interbedded  layers  of  chert.  Much  organic 
matter,  and  more  or  less  bitumen,  are  also  at  times  present.  The 
limestone  seems  to  have  been  raised  above  the  ocean  level  at  the 
close  of  the  Lower  Carboniferous  and  to  have  remained  for  a  long 
period  exposed  to  the  atmospheric  agents.  Much  caving  in  of 
unsupported  layers  of  chert  and  much  attendant  brecciation  re- 
sulted. The  general  stratum  became  quite  open  and  cellular  in 
certain  portions.  At  a  later  period,  supposed  from  several  indica- 
tions to  be  at  the  close  of  the  Cretaceous,  dynamic  disturbance 
occurred,  which  along  certain  lines  produced  fissures,  sometimes 
parallel,  sometimes  intersecting.  Solutions  arose  through  these 
which  dolomitized  much  of  the  remaining  limestone  and  caused 
additional  porosity.  Zinc  and  lead  ores  were  afforded,  and  where 
the  conditions  were  favorable  they  spread  laterally  from  the  fis- 
sures and  deposited  the  sulphides  in  the  cellular  rock  or  replaced 
the  limestone  itself.  The  intersection  of  crossing  fissures  is  a  fre- 
quent point  of  deposition,  and  at  times  parallel  master  fissures 
have  given  a  wide  area  of  impregnation.  This  form  of  ore  fa- 


LEAD  AND  ZINC.  171 

posit  is  called  a  run.  The  runs  are  from  5  to  50  feet  in  height, 
100  to  300  feet  long,  and  10  to  50  feet  across.  At  Webb  City 
they  are  even  larger.  As  a  general  thing  the  ore  is  in  the  inter- 
stices of  the  brecciated  chert,  but  it  is  also  in  limestone  and  dolo- 
mite, and  associated  with  a  silicified  form  of  the  insoluble  residue 
left  by  the  solution  of  the  limestone,  which  Dr.  Jenney  calls 
"  cherokite."  All  the  ores  require  concentration.  Galena  usually 
occurs  ifl^r  the  surface,  while  blende  is  more  abundant  in  depth. 
Cadmium  is  at  times  present  in  the  blende  in  notable  amount. 

2.06.08.  Some  interesting  alterations  of  the  minerals  have  oc- 
curred, which  have  changed  the  blende  to  smithsonite  and  cala- 
mine.     In  one  case  a  secondary  precipitation  of  zinc  sulphide  has 
occurred  as  a  white  amorphous  powder  which  is  of  very  recent 
date.     With  the  original  precipitation  of  the  blende  the  asphaltic 
material  may  have  had  something  to  do.    In  the  matter  of  produc- 
tion Dr.  Jenney  fixes  the  ratio  of   the  blende,  galena,  and  pyrite 
at  about  1000  :  80  :  O.5.1 

2.06.09.  Other  zinc  and  lead   deposits  are   known  in  central 
Missouri  generally  resembling  the   above  quite   strongly,  but   of 
less   economic   importance.       Some,    however,    are    described    by 
Schmidt   as  conical  stockworks.      They   sometimes  are  found  in 
Lower  Silurian  strata. 


1  G.  C.  Broadhead,  "Geological  History  of  the  Ozark  Uplift,"  Amer. 
Geol,  III.  6.  H.  M.  Chance,  "The  Rush  Creek  (Arkansas)  Zinc  District," 
Trans.  Amer.  Inst.  Mm.  Eng.,  Washington  meeting,  1890.  F.  L.  Clerc, 
Geological  description  of  the  mines  in  a  statistical  pamphlet  on  the  Lead 
and  Zinc  Ores  of  Southwest  Missouri  Mines,  p.  4,  published  by  J.  M.  Wil- 
son, Carthage,  Mo.,  1887.  Rec.  See  also  Engineering  and  Mining  Jour- 
nal, June  4,  1887,  p.  897.  "  Zinc  in  the  United  States,"  Mineral  Resources, 
1882,  p.  368.  Engineering  and  Mining  Journal,  Nov.  3, 1888,  p.  389  ;  March 
8,  1890,  p.  286.  E.  Haworth,  A  Contribution  to  the  Geology  of  the  Lead 
and  Zinc  Mining  District  of  Cherokee  County,  Kansas,  Oskaloosa,  Iowa, 
1884.  C.  Henrich,  "  Zincblende  Mines  and  Mining  near  Webb  City,  Mo.," 
M.  E.,  February,  1892  ;  Engineering  and  Mining  Journal,  June  4,  1892. 
R.  W.  Raymond,  "Note  on  the  Zinc  Deposits  of  Southern  Missouri,"  M. 
E.,  VIII.  165  ;  Engineering  and  Mining  Journal,  Oct.  4,  1879.  J.  D.  Rob- 
ertson, "A  New  Variety  of  Zinc  Sulphide  from  Cherokee  County,  Kansas," 
Amer.  Jour.  Sci.,  iii.,  XL.,  p.  160.  A.  Schmidt  and  A.  Leonhard,  Missouri 
Geol.  Survey,  1874.  A.  Schmidt,  "Forms  and  Origin  of  the  Lead  and  Zinc 
Deposits  of  Southwest  Missouri,"  Trans.  St.  Louis  Aead.  Sci.,  III.  246; 
Amer.  Jour.  Sci.,  iii.,  X.,  p.  300.  Die  Blei  und  Zink  Erzlagerstatten  von 
Sudwest  Missouri,  Heidelberg,  Germany,  1876.  W.  H.  Seamon,  "Zinc- 
iferous Clays  of  Southwest  Missouri/'  Amer.  Jour.  Sci.,  iii.,  XXXIX.,  p.  38. 


172  KEMP'S    ORE  DEPOSITS. 

2.06.10.  Both  the  mines  of  Example  25  and  those  of  Example 
24  were  originally  worked  for  lead,  and  the  zinc  minerals  were  re- 
garded as  a  nuisance  ;  of  late  years  the  zinc  has  been  much  more 
of  an  object  than  the  lead.     The  deposits  in  southwest  Virginia 
(Example  26)  also  produce  lead,  but  are  best  known  for  zinc. 

2.06.11.  Example  26.  Wythe  County,  Virginia.    Veins  or  beds 
of  oxidized  ores,  probably  changing  to  blende  below  in  crystalline 
limestone  or  dolomite,  just  above  the  Calciferous  but  as  yet  not 
sharply  determined  in  their  stratigraphy.    The  ore-bearing  terrane 
is  known  over  a  considerable  extent  of   country,   running   from 
near  Roanoke   one  hundred  miles  westward.     The  largest   mines 
are  in  Wythe   County,  and  of  these   the   Bertha  is   best   known. 
According  to  Boyd,  there  are  in  one   section   486   feet  of  strata 
impregnated  with  lead    and  zinc  in  varying   amounts.     Farther 
east,  other  openings  of  considerable  promise  have  lately  been  made 
at  Bonsacks.     The  zinc  ore  bodies  are  at  times  of  great  size  (40 
feet  wide),  and  are  associated  with  more  or  less  of  lead  minerals 
and  iron  pyrites.     It  would  appear  as  if  the  region  must  be  an  im- 
portant producer  of  zinc  in  the  future.1 

Dr.  Jenney's  paper  may  be  expected  in  the  Trans.  Amer.  lust.  Min.  Eng. , 
1893. 

1  C.  R.  Boyd,  Resources  of  Southwest  Virginia,  p.  71  ;  "  Mineral 
Wealth  of  Southwest  Virginia,"  M.  E.,  V.  81 ;  Ibid.,  VIII.  340.  Eec.  H. 
Credner,  Zeitschr.  fur  die  gosammten  Naturwissenschaften,  1870,  Vol. 
XXXIV.,  p.  24.  F.  P.  Dewey,  "  Note  on  the  Falling  Cliff  Zinc  Mine," 
M.  E.,  X.  111.  A.  v.  Groddeck,  Typus  Austin,  Lehre  von  den  Lagerstat- 
ten  der  Erze.t  p.  103. 


I 


1 
I 


CHAPTER  VII. 

ZINC  ALONE,  OR  WITH  METALS  OTHER  THAN  LEAD. 

2.07.01.  Zinc  ores  commonly  occur  in  association  with  lead,-but 
there  are  one  or  two  exceptional  deposits  in  this  country  which  are 
without  lead  and  which  have  no  parallel  in  other  parts  of  the  world. 
The  minerals  containing  zinc  at  Franklin  Furnace  and  Ogdens- 
burg,  N.  J.,  are  known  elsewhere  only  as  rarities,  although   they 
are  found  in  vast  amounts  in  New  Jersey.1 

ZINC  SERIES. 

Zn.          S.        Fe.     SiOa.      Mn. 

Sphalerite  (commonly  called  blend*-)  ZnS 67          33 

Zincite,  ZnO 80.3 

Franklinite,(Fe.Zn.Mn)O,(Fe.Mn)8O,  (variable)    5.54  51.8  7.5 

Willemite,  2ZnO.S,O2 58.5  27.1 

Calamine,  2ZnO.SiO2,H2O 54.2  25.0 

Smithsonite,  ZnOCO2 51.9 

2.07.02.  Example    27.     Saucon  Valley,  Pennsylvania.     Zinc- 
blende  and  its  oxidation  products,  calamine  and  smithsonite,  fill- 
ing innumerable  cracks  and  fissures  in  a  disturbed,  magnesian  lime- 
stone, thought  to  belong   to   the    Chazy  stage.     The   ore  bodies 
occur  in  the  Saucon  Valley  near  the  town  of  Friedensville,  about 
four  miles  south  of  Bethlehem.     The  limestone  is  inclosed  between 
two  northerly  spurs  of  the  South  Mountain,  and  has  apparently 
been  tilted  and  shattered  by  the   upheaval   of   the   latter.     The 
shattering  and  disturbances  decrease  as  the  South  Mountain  is  left 
and   the    dip    decreases.      There    are   three   principal   mines,    the 
Ueberroth,  the  Hartman,  and  the  Saucon,  the  first  named  being  in 
the  portion  which  is  tilted  nearly  to  a  vertical  dip  and  is  much  dis- 
turbed, while  the  next  is  where  the  dip  has  gradually  decreased  to 
35°.     The  mines  are  on  a  belt  some  three  quarters  of  a  mile  long. 
At  the  Ueberroth  an  enormous  quantity  of  calamine  was  found  on 

1  F.  L.  Clerc,  ''Zinc  in  the  United  States,"  Mineral  Resources,  1882, 
p.  358. 


ZINC  ALONE.  175 

the  surface,  but  it  passed  in  depth  into  blende  and  was  clearly  an 
oxidation  product.  In  the  others  the  blende  came  nearer  the  sur- 
face. The  ore  follows  the  bedding  planes  and  the  joints  normal  to 
these  throughout  a  zone  varying  from  10  to  40  feet  across  and  fills 
the  cracks.  At  their  intersection  the  largest  masses  are  found. 
Six  larger  parallel  fissures  were  especially  marked  at  the  Ueberroth. 
This  mine  proved  in  development  to  be  very  wet,  and  a  famous 
pumping  engine,  the  largest  of  its  day,  was  built  to  keep  it  dry. 
The  Hartman  and  Saucon  are  less  wet.  A  little  pyrite  occurs  with 
the  blende,  and  thin,  powdery  coatings  of  greenockite  sometimes 
appear  on  its  surface,  but  it  is  entirely  free  from  lead  and  a  very 
high  grade  spelter  is  made  from  it.  The  mines  were  strong  pro- 
ducers from  1853  to  1876,  but  little  has  been  done  since.  It  is  re- 
ported (1891)  that  the  great  pumping  engine  has  been  started,  and 
they  may  once  more  furnish  considerable  quantities  of  ore. 

2.07.03.  The  mines  were  evidently  filled  by  circulations  from 
below  that  brought  the  zinc  ore  to  its  present  resting  place  in  the 
shattered  and  broken  belt.     Drinker  considers  it  to  have  been  de- 
rived from  a  disseminated  condition  in  the  limestone.1 

2.07.04.  Example  28.     Franklin  Furnace  and  Sterling,  N.  J. 
A  bed  consisting  of  franklinite,  willemite,  zincite,  etc.,  in  crystal- 
line limestone,  in  many  respects  analogous  to  the  magnetite  of  Ex- 
ample 13.     The  franklinite  and  zincite  beds  are  in  a  belt  of  white, 
crystalline  limestone  which  runs  southwesterly  from  Orange  County, 
New  York,  across  northwestern  New  Jersey.     It  was  considered 
metamorphosed  Lower  Silurian  by  H.  D.  Rogers,  but  its  associa- 
tion with  Archaean  gneiss  is  so  close  that  it  has  with  some  reason 
been  regarded  as  of  the   same  age   with  the  gneiss.     Beyond  the 
gneiss  to  the  west  a  blue  limestone  supposed  to  be  Lower  Silurian 
outcrops,  and  the  same  rock  appears  again  to  the  southeast.     F.  L. 
Nason,  of  the  New  Jersey  Survey,  has  recently  argued,  after  careful 

,and  praiseworthy  field  work,  and  after  discovering  in  unmetamor- 
phosed  portions  some  fossils  which  belong  to  the  Olenellus  fauna  of 
the  Cambrian,  that  the  blue  and  white  limestones  are  of  the  same 
age,  and  that  the  latter  owes  its  character  to  a  great  dike  of  granite, 


1  F.  L.  Clerc,  Mineral  Resources,  1882,  361.  Rec.  H.  S.  Drinker. 
"On  the  Mines  and  Works  of  the  Lehi-h  Zir.c  Company,"  M.  E.,  I.  67, 
C.  E.  Hall,  in  Rep.  D3,  Second  Geol.  Survey  Penn.,  p.  239.  Die  Gruben 
und  Werke  der  Lehigh  Zink  Gesellschaft  in  Peansylvanien,  B.  und  IT* 
Zeit.,  1872,  p.  51. 


176  KEMP'S  ORE  DEPOSITS. 

which  appears  at  various  points.  The  granite  is  not  always  con- 
tinuous, and  is  often  in  isolated  masses  or  horses,  as  in  the  Trotter 
mine.  There  is  also  in  some  portions  of  the  belt  a  curious  scapo- 
lite  rock,  regarded  as  igneous.  It  is  not  unlikely  that  the  great 
dikes  may  have  been  a  factor  in  the  formation  of  the  ore,  although 
this  is  not  demonstrated.  At  Franklin  Furnace  the  crystalline 
limestone  forms  a  low  hill  (Mine  Hill)  east  of  the  upper  waters  of 
the  Wallkill,  and  again  at  Ogdensburg,  two  miles  south,  another 
(Sterling  Hill),  on  the  west  bank.  There  is  a  valley  and  unex- 
posed  strip  between,  so  that  the  unbroken  continuity  without  a 
possible  intervening  fault  cannot  «be  established.  The  bed  at 
Franklin  outcrops  on  the  west  side  of  the  hill.  It  begins  on  the 
north  just  across  the  Hamburg  road  and  runs  south  30°  west  as  a 


FIG.  45. — Section  at  Franklin  Furnace,  N.  J.,  showing  the  geological  re- 
lations of  the  franklinite  ore  body.    After  F.  L.  Nason,  Geol.  of 
N.  J.,  1890,  XIV.,  p.  50.     The  ore  body  is  in  ivhite  lime- 
stone with  underlying  gneiss. 

\ 

continuous  bed  for  about  2500  feet.  This  portion  is  called  the 
Front  vein.  It  contains  on  the  north  the  old  Hamburg  mine, 
then  the  Trotter  mine,  and  in  the  southern  portion  belongs  to  the 
New  Jersey  Zinc  and  Iron  Company.  It  runs  from  8  to  30  feet 
broad  at  the  outcrop,  but  swells  below.  It  dips  southeast  40  to  60° 
into  the  hill,  and  is  interbedded  in  the  limestone.  In  the  Trotter 
mine  a  wedge  or  horse  of  hornblende,  augite,  plagioclase,  and 
various  other  silicates  enters  the  bed  a  short  distance.  In  this 
horse  some  of  the  most  interesting  minerals  have  been  found,  such 
as  fluorite,  rhodonite,  blende  (var.  cleiophane),  smaltite  (var. 
chloanthite),  axinite,  etc.  At  the  end  of  the  Front  vein — or,  more 
properly,  bed— a  branch  or  bend  strikes  off  at  an  angle  of  30  to  40° 
to  the  west.  This  more  easterly  branch,  which  is  called  the  Buck- 
wheat mine,  outcrops  on  the  surface  some  500  feet,  and  then,  after 
being  cut  by  a  trap  dike  22  feet  wide,  pitches  down  at  an  angle  of 
27°  and  passes  under  the  limestone.  The  portion  of  the  mine  north- 
east of  the  dike  furnishes  the  most  and  best  ore.  The  surface  out- 


ZIXC  ALONE.  Ill 

crop  of  the  Buckwheat  was  25  to  30  feet  across,  but  it  swelled  be- 
low to  52  feet,  and  in  the  second  level,  about  200  feet  from  the 
surface,  it  was  penetrated  by  a  cross-cut  125  feet  without  finding 
the  wall.  The  character  of  the  ore  varies  ;  for  while  it  is  excellent 
at  the  point  of  the  cross-cut,  at  125  feet  nearer  the  intersection  with 
the  front  bed  it  becomes  lean,  while  preserving  its  width  lower. 
Beyond  the  dike  the  bed  is  likewise  broad,  and  is  mined  out  for  40 
to  50  feet  across.  The  workings  are  now  some  distance  down  on 
the  pitch.  The  impression  made  by  the  arch  of  the  roof  and 
by  the  curving  beds  is  that  this  is  the  crest  of  an  anticline 
whose  axis  pitches  north  27°,  and  whose  central  portion  is  formed 
by  the  franklinite  bed  being  doubled  up  together  on  itself  be. 
fore  the  two  parts  diverge  in  depth.  Its  western  portion  probably 
is  continuous  in  a  synclinal  trough  with  the  front  bed,  and  its 
eastern  portion  dips  east  at  some  unknown  angle.  If  this  is  true, 
it  would  doubtless  be  struck  by  drilling  in  the  surface  to  the  east- 
ward. Mining  has  generally  been  followed  along  the  entire  out- 
crop except  at  the  junction  of  the  twro  branches.  At  present  the 
most  active  work  is  being  done  on  the  front  bed  at  the  Trotter 
mine  and  on  the  rear  bed  of  the  Buckwheat,  the  latter  being  much 
the  larger. 

2.07.05.  The  ore  consists  of  franklinite  in  black  crystals^ 
usually  rounded  and  irregular,  but  at  times  affording  quite  a  per- 
fect octahedron  combined  with  the  rhombic  dodecahedron  and  set 
in  a  matrix  of  zincite,  willemite,  and  calcite.  The  richest  ore  lacks 
the  calcite  and  consists  of  the  other  three  in  varying  proportions. 
This  best  ore  is  in  largest  amount  in  the  Buckwheat  mine,  beyond 
the  trap  dike  which  cuts  it.  The  limestone  containing  the  ore  has 
a  notable  percentage  of  manganese  replacing  the  calcium,  and 
where  it  is  exposed  to  the  atmosphere  it  weathers  a  characteristic 
brown.  An  analysis  of  a  sample  occurring  with  the  ore  at  Sterling 
Hill  afforded  F.  C.  Van  Dyck  : 

CaCO3 82.23 

MnCO3   16.57 

Fes08 0.50 

Si02 0.20 

H26 1.0 


100.50 


The  percentage  of  manganese  is  very  high  for  a  limestone. 

2.07.06.    The  Sterling  Hill  outcrop  is  less  extensive.    It  begins 


on 


178  KEMP'S   ORE  DEPOSITS. 

the  north  with  the  New  Jersey  Zinc  and  Iron  Company's  property 
and  runs  south  30°  west  for  1100  feet.  It  then  branches  or  bends 
around  to  the  west  and  runs  north  60°  west  for  300  feet,  bend- 
ing again  to  north  30°  east,  and  pitches  beneath  the  surface. 
Thus  the  general  relations  between  the  front  and  back  beds 
are  somewhat  the  same  as  at  Mine  Hill,  and  the  dip  and  pitch 
are  similar.  The  principal  workings  are  on  the  Front  vein,  where 
there  are  two  veins  (beds),  according  to  the  older  descriptions,  one 
rich  in  franklinite  and  the  other  in  zincite.  It  is  doubtful  if  there 
really  are  two  distinct  beds,  but  probably  one  portion  is  richer  in 
zincite  than  the  other.  The  part  mined  is  from  two  to  ten  feet. 
The  footwall  is  corrugated  and  causes  many  pinches  and  swells, 
whose  troughs  pitch  north.  The  limestone  between  the  front  and 
back  outcrop  is  charged  with  franklinite  and  various  silicates  (jef- 
fersonite,  augite,  garnets,  etc.),  and  has  been  mined  out  in  large 
open  cuts  now  abandoned.  A  deposit  of  calamine  was  found  in 
the  interval  about  1876,  and  has  furnished  many  fine  museum 
specimens. 

2.07.07.  It  is  not  clear  that  the  Sterling  Hill  and  Mine  Hill 
deposits  were  once  continuous.     The  bed  at  Mine  Hill  runs  in  the 
front  portion  close  to  the  contact  of  the  white  limestone  and  the 
gneiss.     The  Sterling  Hill  bed   is  much  farther  away  from  the 
gneiss,  and  this  would  indicate  that  it  is  at  a  higher  horizon.     The 
evidence,  too,  of  a  pitching  syncline  is  strong,  but  a  pitching  S-fold 
is  not  as  clear.     A  faulting  of  the  Archaean  rocks  in  an  east  and 
west  line  across  their  strike,  and  a  subsequent  tilting  so  as  to  give 
them  a  northerly  pitch,  is   a  very  widespread  phenomenon  in  the 
Highlands,  and  lends  weight  in  this  instance  to  the  idea  that  a  fault 
intervenes  between  the  two  hills.     Such  faulting  is  shown  even  in 
New  York  City. 

2.07.08.  The  origin  of  these  beds  is  very  obscure.    They  are  so 
unique  in  their  mineralogical  composition  that  very  little  direct 
aid  is  furnished  by  deposits  elsewhere.     At  Mine  Hill,  below   the 
fork  of  the  franklinite  bed,  there  was  formerly  a  large  lense   of 
magnetite  that   has  now  been  mined  out.     It  was  in  the  white 
limestone.     There  are  many  points  of  analogy  between  the  frank- 
linite beds  and  extended  magnetite  deposits.     They  are  both  min- 
erals of  the  spinel  group,  and  the  spinels  are  a  common  result  of 
metamorphic  action.     The  presence  of  zincite  and  willemite  com- 
plicates matters,  however,  and  while  an  original  ferruginous  de- 
posit might  be  conceived  with  a  large  percentage  of  manganese, 


ZINC  ALONE.  119 

yet  such  abundance  of  zinc  is  beyond  previous  experience.  It  is, 
however,  suggestive  that  no  inconsiderable  amount  of  zinc  is  found 
in  the  Low  Moor  (Va.)  limonites,  as  shown  by  the  flue  dust  (see 
E.  C.  Means,  "  The  Dust  of  the  Furnaces  at  Low  Moor,  Va.,"  Buf- 
falo meeting  Amer.  Inst.  Min.  Eng.,  October,  1888),  and  this 
in  the*  course  of  a  protracted  blast  may  amount  to  many  tons, 
but  it  does  not  approach  the  Franklin  Furnace  ores.  None  the 
less,  in  the  absence  of  a  better  explanation,  the  franklinite  bed 
may  be  thought  of  as  perhaps  an  original  manganese,  zinc,  iron  de- 
posit in  limestone,  much  as  many  Siluro-Cambrian  limonite  beds 
are  seen  to-day,  and  that  in  the  general  metamorphism  of  the  re- 
gion it  became  changed  to  its  present  condition.  Minerals  of  the 
spinel  group  occur  all  through  this  limestone  belt,  and  in  Orange 
County,  New  York,  to  the  north,  there  is  an  old  and  prolific  source 
of  them. 

2.07.09.  If  it  is  possible  to  demonstrate  the  connection  between 
the  white  limestone  and  a  granite  dike,  as  Mr.  Nason  argues,  this 
may  have  been  an  important  factor  in  the  ore  formation.     It  is 
very  reasonable  that  the  igneous  intrusion  should  start  ore-bearing 
currents  along  a  certain  stratum  in  the  limestone,  which  would  re- 
place it  with  ore.     Subsequent  folding  and  metamorphism  must 
then  have  changed  these  ores,  whatever  they  were,  to  the  present 
unusual  minerals.1 

2.07.10.  Blende  is   known  in  numerous  places  in  the  Rocky 
Mountains  and  is  often  argentiferous,  but  it  is  not  as  yet  profit- 
ably smelted  for  zinc,  and  is  a  drawback  to  the  lead-silver  pro- 
cess. 

2.07.11.  A  large  amount  of  zinc  ore  is  turned  directly  into  zinc 
white  and  employed  as  a  pigment.     For  this  reason  later  statistics 
of  the  metal  do  not  indicate  all  the  ore  mined.     The  accompany- 
ing figures  are  short  tons.     For  detailed  statistics  see  the  volume  on 
"  Mineral  Industry "   of  the   Engineering  and  Mining  Journal, 
1893. 


1  F.  Alger,  "  On  the  Zinc  Mines  of  Franklin,  Sussex  County,  N.  J.," 
Amer.  Jour.  Sci.,  i.,  XL VIII.  252.  Bemis  and  Woolson,  An  unpublished 
thesis  in  the  School  of  Mines  Records,  1885.  H.  Credner,  "  On  the  Frank- 
linite Beds,"  B.  und  H.  Zeit.,  1866,  29,  and  1871,  369.  Geol.  of  New  Jersey, 
1868  (with  a  map),  and  subsequent  Annual  Reports.  F.  L.  Nason,  Ann. 
Rep.  State  Geol.  N.  J.,  1890,  p.  25.  Rec.  Amer.  Geol.,  VIII.  166.  Van- 
uxem  and  Keating,  "  On  the  Geology  and  Mineralogy  of  Franklin,  Sussex 
Oounty,  N.  J.,"  Phil.  Aead.  Sci.,  Vol.  II.,  p.  277. 


180  KEMPS  ORE  DEPOSITS. 

1882.  1890. 

Illinois 18,201  26,243 

Kansas 7.366  15,199 

Missouri 2,500  13,127 

Eastern  and  Southern  States 5,698  9,114 

33,765  63,683 

These  amounts  are  from  the  Mineral  Resources  of  the  United 
States,  1889-90,  p.  89. 


CHAPTER  VIII. 

LEAD    AND    SILVER. 

2.08.01.  There  are  two  general  methods  of  extracting  silver 
from  its  ores,  the  one  indirectly,  by  smelting  with  and  for  lead  ; 
the   other  by  amalgamation,  chlorination,  or  some  such  process. 
Hence  under  silver  there  are  two  classes  of  mines — lead-silver  and 
high-grade  silver  ores.     Both  have  almost  always  varying  amounts 
of  gold.     The  lead-silver  mines  furnish  also,  as  noted  above,  by 
far  the  greater  portion  of  the  lead  produced  in  the  United  States. 
Ores  adapted  to  lead-silver  metallurgical  treatment  form,  in  gen- 
eral, the  oxidized  alteration  products  of  the  upper  parts  (above 
permanent  water  level)  of  deposits  of  galena  and  pyrites.     They 
may  be  well-marked  fissure  veins,  chimneys,  chambers,  or  contact 
deposits.     Ores   which  of   themselves  are   adapted  to  other  pro- 
cesses are  often  worked  in  with  the  lead  ores,  and  unchanged  sul- 
phides are  artificially  oxidized  by  roasting  preparatory  to;  smelt- 
ing.     The  localities   are  taken  up  geographically   from   east   to 
west. 

2.08.02.  LEAD-SILVER  DEPOSITS   IN   THE   ROCKY   MOUNTAIN 
REGION  AND  THE  BLACK  HILLS. — The  mines  are  described  in  order 
from  south  to  north,  beginning  with  New  Mexico. 

NEW  MEXICO. 

2.08.03.  Example  29.     The  Kelley  Lode.     Oxidized  lead  ores, 
with  some  blende,  calamine,  etc.,  forming  a  contact  deposit  be- 
tween slates  and  porphyry.     The  ore  body  is  in  the  Magdalena 
Mountains,    thirty  miles  west  of  Socorro,   and  has  supplied  the 
Billings  smelter  at  that  point.     Numerous  other  ore  bodies  along 
the  contact  between  sedimentary  and  eruptive  rocks  occur  in  the 
same  region. 

2.08.04.  Example  29a.    Lake  Valley.    Farther  south,  in  Dona 
Ana  County,  the  mines  of  Lake  Valley  afford  lead  ores  on  the 
bedding  planes  of  limestone  and  along  the  contact  between  it  and 


182  KEMPS   ORE  DEPOSITS. 

various  igneous  rocks.  Considerable  carbonate  of  iron  is  asso- 
ciated with  them,  and  a  variety  of  rare  minerals,  including  vanadi- 
nite,  descloizite,  etc.,  occur.  The  limestones  are  probably  Subcar- 
boniferous.  There  are  other  districts  in  the  territory  of  minor 
importance.1 

COLORADO. 

2.08.05.  Example  30.  Leadville.  Bodies  of  oxidized  lead- 
silver  ores,  passing  in  depth  into  sulphides,  deposited  in  much 
faulted  Carboniferous  limestone,  in  connection  with  dikes  and 
sheets  of  porphyry.  Leadville  is  situated  in  a  valley  which  is 
formed  by  the  head  waters  of  the  Arkansas  River.  The  valley 
runs  north  and  south,  being  confined  below  by  the  closing  in  of 
the  hills  at  the  town  of  Granite.  It  is  about  twenty  miles  lon^ 
and  sixteen  broad,  and  even  to  superficial  observation  is  seen  to  be 
the  dried  bottom  of  a  former  lake.  The  mountains  on  the  east 
form  the  Mosquito  range,  a  part  of  the  great  Park  range,  while 
those  on  the  west  are  the  Sawatch,  and  constitute  the  Continental 
Divide  at  this  point.  Leadville  itself  is  on  the  easterly  side,  upon 
some  foothills  of  the  Mosquito  range.  The  eastern  slope  of  the 
Mosquito  range  rises  quiter  gradually  from  the  South  Park  to  a 
general  height  of  13,000  feet.  The  range  then  forms  a  very  ab- 
rupt crest,  with  steep  slopes  looking  westward,  which  are  due  to  a 
series  of  north  and  south  faults  whose  easterly  sides  have  been 
heaved.upward  as  much  as  7500  feet.  The  faults  pass  into  anti- 
clines along  their  strike.  The  Mosquito  range  consists  of  crystal- 
line Archaean  rocks,  foliated  granites,  gneisses,  and  amphibolites 
and  of  over  5000  feet  of  Paleozoic  sediments  and  igneous  rocks. 
The  former  include  Cambrian  quartzite,  150  to  200  feet;  Silurian 
white  limestone,  160  feet,  and  quartzite,  40  feet ;  Carboniferous 
blue  limestone,  200  feet  (the  chief  ore-bearing  stratum)  ;  Weber 
shales  and  sandstones,  2000  feet;  and  Upper  Carboniferous  lime- 
stones, 1000  to  1500  feet.  The  igneous  rocks  are  generally  por- 
phyries. The  sedimentary  rocks  were  laid  down  in  Paleozoic  time 
on  the  shores  of  the  Archaean  Sawatch  island,  and  were  penetrated 
by  the  igneous  rocks,  probably  at  the  close  of  the  Cretaceous. 
They  were  all  upheaved,  folded,  and  faulted  in  the  general  eleva- 
tion of  the  Rocky  Mountains,  about  the  beginning  of  the  Tertiary 
period.  The  intrusion  of  the  igneous  rocks  was  the  prime  mover 

1  Rep.  Director  of  the  Mint,  1882,  pp.  341,  376.     B.  Silliman,  "  Mineral 
Regions  of  New  Mexico,"  M.  E.,  X.  224. 


LEAD  AND  SILVER.  183 

in  starting  ore  deposition,  and  the  solutions  favored  the  under  side 
of  the  sheets,  along  their  contacts  with  the  blue  Carboniferous 
limestone. 

2.08.06.  The   early  "history  of  Leadville  will  be  subsequently 
referred  to  in    speaking   of  auriferous    gravels.      The  lead-silver 
ores  first  became  prominent  in  1877,  although  discovered  in  1874, 
and  by  1880  the  development  was  enormous.     The  region  grew  at 
once  to  be  the  largest  single  producer  of  these  ores,  and  has   re- 
mained such  ever  since.     The  mines  are  situated  east  of  the  city 
on  the  three  low  hills,  Fryer,  Carbonate,  and  Iron,  but  recently  a 
deep  shaft  in   the  city  itself  has   found    the  extension  of  the  ore 
chutes  and  opened  up  great  future  supplies.    The  ores  have  chiefly 
come  in  the  past  from  the  upper  oxidized  portions  of  the  deposits. 
Of  late  years,  however,  the  older  and  deeper  workings  have  been 
showing  the  unchanged  sulphurets.     The   ores  are   chiefly  earthy 
carbonate  of  lead,  with  chloride  of  silver,  in  a   clayey  or  siliceous 
mass  of  hydrated  oxides  of  iron  and  manganese.     In  the  Robert 
E.  Lee  mine  silver  chloride  occurred  without  lead.     Some  zinc  is 
also  found,  and  a  long  list  of  rare  minerals.     Where  the  ore  is  in 
a  hard,  siliceous,  limonite  gangue  it  is  called  hard  carbonate,  but 
where   it  is  sandy  and  incoherent   it  forms  a  soft  carbonate,  or 
sand   carbonate.     All  the   mines  produce  small  amounts  of  gold, 
which  in  one  case  (the  Printer  Boy)  has  been  of  more  importance 
than  the  silver.     A  few  ore  bodies  are  found  at  other  horizons 
than  the  Carboniferous.     They  also  run  in  instances  as  much  as 
100  feet  from  the  contact,  and  may  likewise  be  found  in  the  por- 
phyry, doubtless    replacing   included    limestone.     They  were   all 
deposited  as  sulphides,  and,  according  to  Emmons,  when  the  rocks 
were  at  least  10,000  feet  below  the  surface. 

2.08.07.  In   the  valuable   monograph  on   the  region,  which  is 
now  a  classic  on  the  subject  and  which  is  cited  below,  Emmons 
endeavors  to  prove  the  following  points  : 

I.  That  the  ores  were  deposited  from  aqueous  solution. 

II.  That  they  were  originally  deposited  mainly  in  the  form  of 
sulphides. 

III.  That  the  process  of  deposition  involved   a  metasomatic 
interchange  with  the  material  of  the  rock  in  which  they  were  de- 
posited. 

IV.  That  the   mineral  solutions  or  ore  currents  were  concen- 
trated along  natural  water  channels,  and  followed,  by  preference, 
the  bedding  planes  at  a  certain  geological  horizon,  but  that  they 


LEAD  AND  SILVER.  185 

also  penetrated  the  adjoining  rocks  through  cross  joints  and  cleav- 
age cracks. 

These  additional  points  are  also  advanced: 

I.  That  the  solutions  came  from  above. 

II.  That    they  were   derived   mainly    from   the   neighboring 
eruptive  rocks. 

2.08.08.  The  first  four  points  are  doubtless  correct,  and  No. 
III.  is  an  important  application  of  the  theory  of  replacement,  fre- 
quently referred  to  in  the  introduction.    The  last  two  propositions 
merit  less    confidence.      Seven    additional   years  of  mining   have 
brought  many  new  facts  to  light  and  have  led  others  (A.  A.  Blow 
in  particular,  whose  valuable  paper  is   cited  below)  to  refer  the 
ores  to  upward  rising  currents.     Emmons  foresaw  this  possibility 
and  mentioned  it  on  p.  584  of  his  monograph.     The  amount  of  the 
adjacent,  igneous  rocks  is  quite  insufficient  to  afford  the  ore.     In 
alteration  the  galena  has  passed  through  an  intermediate  stage  of 
sulphate  before  changing  to  carbonate.      These  mines  have  been 
important  not  alone  in   their  own    metallic  products,  but  in  fur- 
nishing  the    smelters    with    oxidized    lead    ores    they    have    sup- 
plied a  means  of  reduction  for  many  other  more  refractory  ones, 
which  could  be  conveniently  beneficiated  through  the  medium  of 
lead.1 

2.08.09.  Example  30a.     Ten  Mile,  Summit  County.      Bodies 


1  F.  M.  Amelung,  "The  Geology  of  the  Leadville  Ore  District,"  Engi- 
neering and  Mining  Journal,  April  16, 1880,  p.  25.  "  On  the  Origin  of  the 
Ore,"  Ibid.,  Dec.  20,  1879.  A.  A.  Blow,  "The  Geology  and  Ore  Deposits 
of  Iron  Hill,  Leadville,  Colo.,"  M.  E.,  June,  1889.  Rec.  Ann.  Rep.  Colo. 
School  of  Minea,  1887,  p.  62.  S.  F.  Emmons,  "Geology  and  Mining  Indus- 
try of  Leadville,"  Monograph  12,  U.  S.  Geol.  Survey.  Rec.  Second  Ann. 
Rep.  Director  of  U.  S.  Geol.  Survey.  Rec.  Tenth  Census,  Vol.  XIII.,  p. 
76.  F.  T.  Freeland,  "  The  Sulphide  Deposits  of  South  Iron  Hill,  Lead- 
ville," M.  E.,  XIV.  181.  C.  Henric  h,  "  The  Character  of  the  Leadville  Ore 
Deposits,"  Engineering  and  Mining  Journal,  Dec.  27,  1879,  p.  470.  "Ori- 
gin of  the  Leadville  Deposits,"  Engineering  and  Mining  Journal,  M..y 
12,  1888,  p.  33.  "On  the  Evening  Star  Mine,"  Ibid.,  May  7,  1881,  p.  361. 
"Leadville  Geology,"  Ibid.,  June  3  and  10,  1882  ;  Historical,  May  30,  April 
6,  13,  20,  27,  1878  ;  also  many  other  allusions,  1879-81.  R.  W.  Raymond, 
Rep.  on  the  Little  Pittsburg  Mine,  Engineering  and  Mining  Journal,  June 
28,  1879.  L.  D.  Ricketts,  The  Ores  of  Leadville,  Princeton,  1883.  C.  M. 
Rolker,  "  Notes  on  Leadville  Ore  Deposits,"  M.  E.,  XIV.  273,  949.  F.  L. 
Vinton,  "  Leadville  and  the  Iron  Mine,"  Engineering  and  Mining  Journal, 
Feb.  15,  1879,  p.  110 ;  also  June  28,  p.  465. 


186  KEMP'S   ORE  DEPOSITS. 

of  argentiferous  galena,  pyrite,  and  blende,  in  beds  of  Upper  Car- 
boniferous limestone,  on  their  contact  with  overlying,  micaceous 
sandstones,  or  with  sheets  and  dikes  of  porphyry.  The  Carbonif- 
erous limestones  that  contain  the  ores  at  Leadville  extend  both 
north  and  south,  and  their  equivalents  occur  also  on  the  west 
flank  of  the  Sawatch  range.  Ten  Mile  is  another  productive  por- 
tion, north  of  Leadville  and  at  a  higher  altitude.  The  strata  are 
enormously  disturbed,  and  pierced  even  more  than  at  Leadville 
by  sheets  and  dikes  of  porphyry.  The  ores  are  less  oxidized  and 
more  rebellious.  The  Robinson  is  the  principal  mine.1 

2.08.10.  Example    30#.     Monarch    District,    Chaffee    County. 
Oxidized  lead-silver  ores  in   limestone.     The  .belt  of   limestones 
south  from  Leadville  contains  some  notable  ore  bodies  in  Chaffee 
County.     The  Monarch  district  is  the  most  important.    It  is  situ- 
ated at  the  head  waters  of  a  branch  of  the  South  Arkansas  River. 
The  ore  lies  in  limestones  whose   age  is  not  yet   accurately  deter- 
mined.    The  Madonna  mine  is  the  best  known   and  has   shipped 
much  ore  to  Pueblo.2 

2.08.11.  Example  30c.     Eagle  River,  Eagle  County.     Galena 
-and  its  alteration  product,  anglesite,  in   Carboniferous  limestone, 
on  the  contact  between  it  and  quartzite  or  porphyry.     The  mines 
lie  in  the  valley  of  Eagle  River,  on  the  western  slope  of  the  Con- 
tinental Divide.     The  galena  has  changed  to  the  sulphate,  instead 
of  carbonate,  probably  having  been  less  completely  oxidized  than 
at  Leadville,  and  marking  the  intermediate  stage  in  the  process. 
The  wall  rocks  lie  quite  undisturbed,  having  a  low  dip  of   15° 
north,  and  not  being  faulted.     Lying  lower  than  the  lead-silver 
deposits,    and   in    Cambrian   quartzite,    on    the   contact    with    an 
overlying  sandstone  are  found  chutes  carrying  gold   in   talcose 
clay.3 

2.08.12.  Example   3Qd.     Aspen,    Pitkin    County.      Bodies    of 


1  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  73  ;  also  a  forthcoming 
monograph  of  the  U.  S.  Geol.  Survey. 

2  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  79.     Rep.  Director  of 
the  Mint,  1884,  p.  191. 

8  S.  F.  Emmons,  "  Notes  on  Some  Colorado  Ore  Deposits,"  Colo.  Sci. 
Soc.,  Vol.  IL,  Part  II.,  p.  100.  E.  E.  Olcott,  "Battle  Mountain  Mining 
District,  Eagle  County,  Colorado,"  Engineering  and  Mining  Journal, 
June  11,  1887,  pp.  417,  436;  Ibid.,  May  21,  1892,  p.  545.  G.  C.  Tilden, 
"Mining  Notes  from  Eagle  County,"  Ann.  Rep.  Colo.  State  School  of 
Mines,  1886,  p.  129. 


188 


KEMP'S   ORE  DEPOSITS, 


lead-silver  ores,  largely  oxidized,  occurring  with  much  barite, 
chiefly  along  the  contact  between  extensively  faulted,  Lower  Car- 
boniferous, blue  limestone  and  a  brown,  dolomitized,  underlying 
portion  of  the  same;  but  also  in  fissures  and  less  regular  deposits 
in  these  and  older  limestones  and  quartzite.  Aspen  is  on  the  west- 
ern slope  of  the  Continental  Divide,  in  the  valley  of  the  Roaring 
Fork,  just  at  the  point  where  it  crosses  the  contact  of  crystal- 
line Archsean  gneisses  and  Paleozoic  sediments.  The  stream  cuts 
them  at  right  angles  to  the  strike.  Aspen  Mountain  lies  on  the 
south  side  and  Smuggler  Mountain  on  the  north.  The  limestone 
belt  continues  north  and  south,  and  is  prospected  over  a  stretch  of 
nearly  forty  miles.  At  Aspen  there  is  evidence  of  a  faulted,  syn- 


ARCHXEAN 

Canon  of  Roaring  Fork 


CAMBRIAN      SILURIAN    CARBONIFEROUS 


CARBONIFEROUS  AND  SILURIAN 

MIDDLE  AND  LOWER  CARBONIFS. 


FIG.  48. — Geological  section  at  Aspen,  Colo.     After  A.  Lakes,  Ann.  Rep. 
Colo.  School  of  Mines,  1886. 


clinal  fold,  with  many  minor  disturbances.  The  westerly  dipping 
rocks  by  the  faulting  are  repeated  to  the  west  and  are  pierced  by 
a  great  granite  intrusion  and  much  porphyry.  Still  farther  west 
the  Red  Jura-Trias  sandstones  are  in  great  force.  The  faulted 
repetitions  of  the  Paleozoic  rocks  are  eroded  into  a  narrow  ridge, 
between  Castle  Creek  and  the  Roaring  Fork,  just  below  the  town. 
Over  beyond  Aspen  Mountain,  and  to  the  south,  lies  Tourtelotte 
Park,  in  a  small  synclinal  basin  of  the  limestones,  and  eight  or 
ten  miles  farther  is  Ashcroft.  The  dips  in  Tourtelotte  Park  are 
low,  but  they  increase  going  down  the  mountain  toward  Aspen, 
and  are  steepest  of  all  at  its  foot,  where  the  strata  at  60°  run  un- 
der the  stream  gravels  and  glacial  deposits.  The  geology  when 
closely  viewed  is  very  complicated,  and  involves  the  following 
sections  according  to  D.  W.  Brunton.  (See  papers  of  W.  E.  New- 
berry  and  S.  F.  Emmons,  cited  on  p.  191.) 


LEAD  AND  SILVER.  189 

BRUNTON. 
Archaean. 

1.  Cambrian  quartzite,  400  feet. 

2.  Silurian  quartzite  and  limestone,  460  feet. 

3.  Lower  Carboniferous  dolomite,  225  feet. 

4.  Lower  Carboniferous  blue  limestone,  110  feet. 

5.  Middle  Carboniferous  (Weber)  shales,  50  to  450  feet. 

6.  Intruded  diorite,  maximum  400  feet. 

7.  Middle  Carboniferous  limestone,  10  to  160  feet. 

8.  Jura-Trias  sandstone. 

E  M  M  o  N  s  . 
Archaean. 

1.  White  quartzite  of  Upper  Cambrian,  200  feet. 

2.  Silurian  limestone  and  sandstone,  340  feet. 

3.  Lower  Carboniferous  brown  and  blue  limestone,  240  feet. 

4.  Middle  Carboniferous  clays  (Weber  shales),  425  feet. 

5.  Middle    Carboniferous   green    and    red    sandstone,    of    the 
Weber  grits,  with  thin  limestone. 

6.  Jura-Trias  sandstone. 

2.08.13.  Two  other  sections  by  different  writers  (Lakes  and 
Henrich)  have  been  published;  but  as  fossils  are  almost  unknown, 
the  strata  can  be  divided  more  or  less  at  will.     The  blue  lime- 
stone is  certainly   Lower  Carboniferous,  for  fossils  gathered  by 
J.  F.  Kemp  from  the  same   horizon  on  Lime   Creek,  twenty-five 
miles  north,  where  they  are  plentiful,  were  pronounced  by  authori- 
ties in  the  East  to  be  such. 

2.08.14.  On  Smuggler  Mountain  the  same  section  is  shown, 
but  it  is  not  broken  by  igneous  rocks;  and  although  there  is  a 
faulting  along  planes  striking  parallel  with  the  beds  and  cutting 
the  dip  at  a  sharp  angle,  the  geology  is  less  complicated. 

2.08.15.  On  Aspen  Mountain  the  ore  bodies  favor  the  contact 
between  the  blue  limestone  and  the  brown  dolomite.     The  former 
is  a  very  pure  limestone,  while  the  latter  contains  from  20  to  28$ 
magnesium  carbonate.     The  ore  replaces  and  impregnates  the  blue 
limestone,  often  with  very  little  change  in  its  appearance,  but  it 
fills  the  numerous  cracks  in  the   more  broken  dolomite,  coating 
larger  and  smaller  blocks.     The  ore  occurs  also  in  minor  fissures. 
On  Smuggler  Mountain  the  ore  especially  follows  the  fissure  veins. 


190  KEMPS    ORE  DEPOSITS. 

To  the  north  the  mines  at  Woody  are  on  a  great  fissure,  according 
to  W.  E.  Newberry  (private  communication),  which  carries  ore 
where  not  filled  "by  a  porphyry  dike.  They  are  of  recent  develop- 
ment, but  promise  to  be  rich.  Although  further  systematic  study 
is  needed,  it  is  quite  clear  that  the  ore  bodies  of  Aspen  Mountain 
have  originated  by  replacement  of  the  blue  limestone  and  by  coat- 
ing the  fragments  of  brown  dolomite.  The  solutions  doubtless 
came  up  along  the  fault  fissures  and  selected  the  contact  for  the 
chief  point  of  deposition.  The  United  States  Geological  Survey 
has  had  a  party  in  the  region.1 

2.08.16.  Example  306.      Rico,  Dolores  County.     Contact  de- 
posits of  lead-silver  ores,  in  Carboniferous  limestones,  along  intru- 
sive  porphyries.     Considerable    base    bullion    has   been    shipped. 
There  are  coals  in  the  vicinity,  but   the  operation   of  the  smelter 
has  been   somewhat  intermittent.     The  Newman  Hill  mines  are 
mentioned  under  "  Silver."  2 

NOTE. — Example  30f  will  be  found  after  Example  31,  which 
has  been  inserted  for  geographical  reasons. 

2.08.17.  Example  31.      Red  Mountain,  Ouray  County.     Oxi- 
dized lead-silver  ores  passing  in  depth  into  sulphides,  in  large  and 
small  cavities,  in   knobs  of   silicified  andesite.     The  cavities  have 
a  close  resemblance  to  caves,  but  differ  from  ordinary  caves  in  not 
being  in  limestone.     They  permeate  the  mountain  in  an  irregular 
way,  and  mark  the  courses  of  old  hot  spring  conduits.     The  ande- 
site is  generally   altered  to  a  mass  of  quartz,  but  the  process  is 
thought   by  Mr.  Emmons  to   have  taken  place  at   a  considerable 
depth,  and   that  the  quartz  is   a  residual  deposit  left  by  the  re- 
moval of  more  soluble  elements  of  the  andesite.     T.  B.  Comstock 
regards  them  as  hot  spring  deposits.3 

1  D.  W.  Brunton,  "Aspen  Mountain:  Its  Ores  and  Mode  of  Occur- 
rence," Engineering  and  Mining  Journal,  July  14  and  21,  1888,  pp.  22,  42. 
S.  F.  Emmons,  "Preliminary  Notes  on  Aspen,"  Proc.  Colo.  Sci.  Soc.,  Vol. 
II.,  Part  III.,  p.  251.     Rec.    C.  Henrich,  "Notes  on  the  Geology  and  on 
Some  of  the  Mines  of  Aspen  Mountain,"  M.  E.,  XVII.  156.    A.  Lakes, 
"  Geology  of  the  Aspen  Mining  Region,"  Ann.  Rep.  Colo.  School  of  Mines, 
1886     W.  E.  Newberry,  "  Notes  on  the  Geology  of  the  Aspen  Mining  Dis. 
trict,"  M.  E.,  June,  1889.     Rec.     L.  D.  Silver,  "Geology  of  the  Aspen 
(Colo.)  Ore  Deposits,"  Engineering  and  Mining  Journal,  March  17  and  24, 
1888. 

2  M.  C.  Ihlseng,  "Review  of  the  Mining  Regions  of  the  San  Juan, '» 
Ann.  Rep.  Colo.  School  of  Mines,  1885,  p.  43. 

8  T.  B.  Comstock,  "  Hot  Spring  Deposits  in  Red  Mountain,  Colorado." 


LEAD  AND  SILVER.  191 

SOUTH    DAKOTA. 

2.08.18.  Example  30/.     Galena  (town),   in  the   Black   Hills. 
Contact  deposits  of  galena,  in  part  altered  to  carbonate,  in  Car- 
boniferous limestone  along  intruded  porphyries.     The  ore  occurs 
in  the  Carboniferous  limestone,  which  overlies  the  Potsdam  sand- 
stone near  Deadwood,  in  the  northerly  flank  of  the  Black  Hills. 
The  principal  localities  are  the  towns  of   Galena  and  Carbonate. 
Sheets  and  dikes  of  igneous  rocks  penetrate  the  limestones  and 
have  occasioned  the  ore  deposits.  Several  smeltery  have  had  some- 
what desultory  campaigns.1 

MONTANA IDAHO. 

2.08.19.  Example  32.     Glendale,  Beaver  Head  County.     Ore 
bodies  of  argentiferous  galena,  zincblende,  copper  and  iron  pyrites, 
and  their  oxidation  products,  occurring  parallel  with  the  stratifica- 
tion planes  of  a  blue-gray  limestone,  of  age  not  yet  determined. 
These  deposits  constitute  the  Hecla  mines,  and  are  in  the  south- 
western part  of  the  State.      They  offer  some  parallel  features  with 
those  of  southeastern  Missouri.     (Example  23.)     They  differ  from 
Example  30  in  not  being  associated,  so  far  as  known,  with  igneous 
rocks.2 

2.08.20.  Example  32a.     Wood   River,  Idaho.     Bodies  of  ar- 
gentiferous galena  and  alteration  products,  irregularly  distributed 
in  limestone,  of  age  as  yet  undetermined.     Southwestern  Idaho  is 
largely  formed  of  granite,  southeastern  is  covered  by  the  immense 
fissure  outpourings  of  basalt  along  the  Snake  River.     North  of 
these,  and  on  the  flanks  of  the  granite,  are  slates  and  limestones, 
especially  on  the  Wood  River.     The  latter  contain  the  lead-silver 
ores.     They  are  not  in  immediate  association  with  igneous  rocks, 
and  from  published  descriptions  appear  to  be  somewhat  irregu- 

M.  E.,  XVIII.  261.  S.  F.  Emmons,  "Notes  on  Some  Colorado  Ore  De- 
posits," Proc.  Colo.  Sci.  Soc.,  Vol.  II.,  Part II.,  p.  97.  M.  C.  Ihlseng,  "Re- 
view of  the  Mining  Interests  of  the  San  Juan  Region,"  Ann.  Rep.  Colo. 
Schoql  of  Mines,  1885,  p.  46.  T.  E.  Schwartz,  "The  Ore  Deposits  of  Red 
Mountain,  Colorado,"  M.  E.,  June,  1889  ;  Proc.  Colo.  Sci.  Soc.,  Vol.  III.,. 
Part  I.,  p.  77. 

1  F.  R.  Carpenter,  "  Ore  Deposits  of  the  Black  Hills  of  Dakota,"  M.E.,. 
1879,  New  York  meeting.     See  also  report  by  Dr.  Carpenter  on  the  geol- 
ogy, etc.,  of  the  Black  Hills,  to  the  trustees  of  the  Dakota  School  of  Mines, 
1888,  p.  124.     S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  91. 

2  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII. ,  p.  97. 


192  KEMP'S   ORE  DEPOSITS. 

larly  distributed,  although  possibly  connected  with  fissures.  The 
structural  relations  with  Example  23  may  again  be  referred  to. 
The  neighboring  slates  and  granite  contain  gold  and  silver  veins, 
which  are  taken  up  later  on.  Several  small  smelters  have  been 
erected  in  the  region,  and  have  been  intermittently  operated. 
The  country  is  really  in  the  northern  end  of  the  Great  Basin.1 

2.08.21.  Example  33.  Wickes,  Jefferson  County,  Mont.  Fis- 
sure veins  near  the  contact  of  granite  and  liparite,  but  cutting 
both  rocks  and  carrying  in  a  gangue  of  quartz  the  ores,  galena, 
zincblende,  copper  and  iron  pyrites,  and  mispickel.  The  liparite 
is  said  by  Lindgren  to  be  Cretaceous  or  Tertiary.  Wickes  is  just 
south  of  Helena,  and  was  one  of  the  first  places  in  the  West  to 
establish  successful  concentration.  There  are  two  companies,  the 
Helena  and  the  Gregory,  both  large  producers. 

/  2.08.22.  Example  34.  Coeur  d'Alene,  Idaho.  Galena  and 
very  subordinate  alteration  products,  in  a  mineralized  zone  having 
a  well-marked  quartzite  footwall  and  an  impregnated,  brecciated 
hanging  of  the  same  rock.  The  ore  is  in  large  chutes,  which  fill 
innumerable  small  fractures  in  the  rock.  The  mines  are  in  Ward- 
ner  Canon,  in  the  Bitter  Boot  Mountains,  northern  Idaho.  The 
rocks  are  quartzite  and  thin  beds  of  schists,  much  folded  along 
east  and  west  axes.  In  this  way  they  became  faulted  and  shat- 
tered, and  in  the  principal  mineral  belt  afforded  an  opportunity  for 
the  ore  to  deposit.  The  gangue  is  siderite.  The  mines  are  ex- 
tremely productive  and  are  the  chief  sources  of  ore  supply  for 
lead  smelters  in  Montana  and  on  the  Pacific  coast.2 

THE  REGION  OF  THE  GREAT  BASIN. 

UTAH. 

2.08.23.  Example  35.  Bingham  and  Big  and  Little  Cotton- 
wood  Canons,  Utah.  Bed  veins,  often  of  great  size,  containing 
oxidized  lead-silver  ores  above  and  galena  and  pyrite  below  the 
water  level,  in  Carboniferous  limestones,  or  underlying  quartzite, 
or  on  the  contact  between  the  two.  The  mines  are  situated  in  the 
Oquirrh  and  Wasatch  Mountains,  southwest  and  southeast  of  Salt 
Lake  City,  in  caflons  well  up  toward  the  summits.  The  region  is 

1  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  55.     Engineering  and 
Mining  Journal,  July  2,  1887,  p.  2.    Rep.  Director  of  the  Mint,  1882,  p.  198. 

2  J.  E.  Clayton,  "The  Cceur  d'Alene  Silver-lead  Mines,"  Engineering 
and  Mining  Journal,  Feb.  11,  1888,  p.  108. 


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194  KEMP'S   ORE  DEPOSITS. 

much  disturbed,  and  there  are  great  faults  and  porphyry  dikes  and 
knobs  of  granite  associated  with  the  sedimentary  rocks.  The  ores 
occur  in  belts,  extending  considerable  distances,  and  these  in  places 
have  the  rich  chutes  or  chimneys  of  oxidized  products.  In  Bing- 
ham  Cafion  an  immense  bed  of  auriferous  quartz  is  found,  overly- 
ing the  lead  zone  and  next  the  hanging.  Some  peculiarity  about 
the  gold  prevents  its  easy  treatment,  but  much  of  the  rock  is  very 
low  grade.  Other  fissure  veins  in  the  massive  rock  of  the  region 
are  known,  but  are  of  less  importance.  The  general  geological 
relations  suggest  the  deposits  mentioned  under  Example  30  and 
subtypes.  The  mines  were  the  occasion  of  the  first  development 
of  the  lead-silver  smelters  in  the  West,  and  have  made  Salt  Lake 
City  an  important  center  of  the  industry.  The  Telegraph  group, 
the  Emma,  Flagstaff,  and  others  were  famous  mines  in  their  day. 
As  will  appear,  nearly  all  the  Utah  mines  are  productive  of  lead- 
silver  ores. 

2.08.24.  Example  35«.  Tooele  County.  Bedded  veins  in 
limestone,  or  between  it  an  1  quartzite,  and  containing  lead-silver 
ores  with  ochers,  in  rich  chutes.  The  deposits  occur  in  the  west 
side  of  the  Oquirrh  range,  in  Ophir  and  Dry  canons,  over  the  di- 
vide from  Bingham.  The  principal  mine  is  the  Honorine.  Fis- 
sure veins  also  occur  in  the  region,  but  are  of  less  importance. 
The  Deep  Creek  district,  near  the  Nevada  line,  is  mentioned  under 
2.11. 04.1 

2.08.25.  Example  35#.  Tintic  District.  Ore  beds  or  belts,  three 
in  number,  and  one  to  three  miles  long,  generally  parallel  with 
the  stratification  of  vertical  blue  limestones,  but  sometimes  run- 
ning across  them.  The  ore-bearing  zone  is  from  300  to  600  feet 
wide  in  at  least  one  belt,  and  bears  in  places  rich  chutes  of  car- 
bonate ore.  The  Crismon-Mammoth  has  been  referred  to  under 


1  W.  P.  Blake,  "Brief  Description  of  the  Emma  MIDP,"  Amer.  Jour. 
Sci.,  ii.,  II.  216.  C.  E.  Fenner,  "The  Telegraph  Mine,"  School  of  Mines 
Quarterly,  July,  1893.  O.  J.  Hollister,  "  Gold  and  Silver  Mining  in  Utah," 
M.  E.,XVl.  3.  Rec.  D.  B.  Huntley,  Tenth  Census,  Vol.  XIII. ,  p.  407. 
G.  Lavagnino,  "The  Old  Telegraph  Mine,"  M.  E.,  XVI.  25.  "  Little  Cotton- 
wood  and  Bingham,  Utah,*'  Engineering  and  Mining  Journal,  Aug.  14, 
1880,  p.  106  ;  also  July  19,  1889.  J.  S.  Newberry,  School  of  Mines  Quarterly, 
1884,  p.  329.  R.  W.  Raymond,  Mineral  Resources  West  of  the  Rocky  Moun- 
tains, 1868-76,  and  J.  R.  Brown,  Ibid.,  1867-68.  Ann.  Reps,  of  Director  of 
the  Mint.  B.  Silliman,  "Geological  and  Mineralogical  Notes  on  Some 
Mining  Districts  of  Utah,"  Amer.  Jour.  Sci.,  iii.,  III.  195. 


LEAD  AND  SILVER.  U5 

"  Copper  "  (Example  20A),  as  it  contains  much  copper.    The  ore  is 
thought  by  Hollister  to  have  replaced  the  limestone.1 

Passing  mention  should  also  be  made  that  lead-silver  ores  occur 
in  Summit  County,  at  the  Crescent  and  other  mines. 

2.08.26.  Example   30g.      Horn   Silver  Mine,   Beaver   County. 
A  great  contact  fissure  between  a   rhyolite  hanging  wall  and  a 
limestone  footwall,  and  carrying,  at  the   Horn  Silver  mine,   oxi- 
dized lead-silver  ores,  chiefly  anglesite,  with   considerable  barite, 
and  with   many   other  rarer  minerals.     The  town  of  Frisco,  con- 
taining the  mine,  is  at   the  southern  end  of  the  Grampian   Moun- 
tains.    The  great  fissure  is  known  for  two  miles,  but  is  proved 
valuable  only   between   the  lines  of    the   Horn   Silver  mine.     It 
strikes  north  and  south   and  dips  70°  east.     In  the  neighborhood 
of  the  vein  the  rhyolite  is  largely  altered  to  residual   clay.     The 
mine  is  very   dry   and  the  entire  region  lacks  good  water.     The 
vein  in  general  varies  from  20  to  60  feet,  but  has  pinched  twice  in 
going  down,  and  of  late  years  has  largely  ceased  producing,  al- 
though there  may  yet  be  much  ore  below.     The   ores  are  smelted 
near  Salt  Lake,  and  the  base  bullion  is  refined  at  Chicago.     Some 
free  milling  ore  has  been  afforded.2 

2.08.27.  Example  33a.     Carbonate  Mine,  Beaver  County.     A 
fissure  vein  in  hornblende  andesite,  filled  with  rounded  fragments 
of  wall  rock,  which  are  cemented  by  residual  clay  and  galena. 
Some  oxidized  products  occur  near  the  surface.     The  mines  are  two 
and  a  half  miles  northeast  of  Frisco,  but  are  in  a  different  eruptive 
rock  from  that  forming  the  walls  of  the  Horn  Silver.     The  literature 
is  the  same  as  for  Example  30</,  especially  Hooker,  1.  c.  p.  470. 

2.08.28.  Example  32&.     Cave  Mine,  Beaver  County.     Cham- 
bers irregularly  distributed  in  the  limestone,  and  more  or    less 
filled  with  limonite  and  oxidized  lead-silver  ores.     Small  leaders 
of  ores,  which  mark  old  conduits,  connect  the  chambers.     Up  to 
1880  five  large  and  fifteen  small  chambers  had  been  found.     They 
are  of  very  irregular  shape,  and  have  a  vacant  space  of  from  one 
to  ten  feet  between  the  ore  and  the  roof.     This  deposit  was  the 
typical  one  cited  by  Newberry  as  illustrating  the  chamber  or  cave 


1  D.  B.  Huntley,  as  above  (footnote,  p.  194) ;  ab-o  O.  J.  Hollister,  as 
above,  under  Example  35a.    J.  S.  Newberry,  Engineering  and  Mining 
Journal,  Sept.  13  and  20,  1879. 

2  O.  J.  Hollister,  "Gold  and  Silver  Mining  in  Utah,"  M.  E.,  XVI.  3. 
Eec.     W.  A.  Hooker,  Report  quoted  in  the  Tenth  Census,  Vol.  XIII.,  p.  464. 

\QftAffi 


196  KEMP'S   ORE  DEPOSITS. 

form  of  deposit.  According  to  this  view,  the  chambers  were 
formed  before  the  ore  was  brought  in.  It  is  also  possible  that  the 
ore  bodies  have  been  deposited  by  replacement  of  the  limestone 
with  sulphides,  as  is  known  abundantly  elsewhere,  and  that  the 
alteration  of  these  to  oxides  has  occasioned  the  apparent  caves. 
The  products  of  the  mine  afford  but  5  to  1%  lead,  but  are  valuable 
as  an  iron  flux  to  the  neighboring  smelters.  The  mines  are  in  the 
Granite  range,  seven  miles  southeast  of  Mil  ford.1 

NOTE. — Although  the  larger  part  of  the  Utah  mines  are  for 
lead  and  silver,  several  others  of  great  importance  will  be  taken 
»up  under  "  Silver  "  itself. 

NEVADA. 

2.08.29.  Example  36.  Eureka.  Bodies  of  oxidized  lead-sil- 
ver ores  in  much  faulted  and  fractured  Cambrian  limestone, 
with  great  outbreaks  of  eruptive  rocks  near.  The  Eureka  geo- 
logical section  is  one  of  the  most  interesting  in  the  entire  country, 
and  involves  some  30,000  feet  of  Paleozoic  strata,  divided  as  fol- 
lows :  Cambrian  quartzite,  limestone,  and  shale,  7700  feet  ;  Silu- 
rian limestone  and  quartzite,  5000  feet  ;  Devonian  limestone  and 
shale,  8000  feet ;  Carboniferous  quartzite,  limestone,  and  conglom- 
erate, 9300  feet.  These  have  afforded  some  extremely  valuable 
materials  for  comparative  studies  with  homotaxial  strata  in  the 
East.  The  ore  occurs  especially  in  what  is  called  the  Prospect 
Mountain  limestone  of  the  Cambrian,  one  smaller  deposit  being 
also  known  in  Silurian  quartzite.  The  limestone  has  been  crushed 
and  shattered  along  a  great  fault,  and  through  its  substance 
ore  solutions  have  circulated,  replacing  it  in  part  with  large 
bodies  of  sulphides  which  have  afterward  become  oxidized  to 
a  depth  of  1000  feet.  The  ore  bodies  were  puzzling  as  regards 
their  classification,  and  a  famous  mining  suit,  with  many  interpre- 
tations from  various  experts,  resulted.  The  alteration  of  the  ore 
has  caused  shrinkage  and  the  formation  of  apparent  caves  over  it. 
But  there  are  many  empty  caves,  formed  by  surface  waters  long 
after  the  ore  was  deposited,  and  Mr.  Curtis  very  clearly  shows 
that  the  ore  bodies  originated  by  replacement.  All  are  connected 

1  O.  J.  Hollister,  "Gold  and  Silver  Mining  in  Utah,"  M.  E.,  1887. 
D.  B.  Hunt  ley,  Tenth  Census,  Vol.  XIII.,  p.  474.  J.  S.  Newberry,  School 
of  Mines  Quarterly,  March,  1880.  Reprint,  p.  9.  Cf.  also  J.  P.  Kimball, 
"The  Silver  Mines  of  Santa  Eulalia,  Chihuahua,"  Amer.  Jour.  Sci  ,  ii., 
XLIX.  161. 


LEAD  AND  SILVER. 


197 


with  more  or  less  strongly  marked  fissures  which  formed  the  con- 
duits. Mr.  Curtis  made  a  careful  series  of  assays  of  the  neigh- 
boring igneous  rocks  to  find  some  indication  of  the  source  of  the 
ore.  A  quartz  porphyry  gave  significant  results  and  to  this  the 
metals  are  referred,  but  the  portions  of  the  mass  at  a  great 


FIG.  50. — Section  at  Eureka,  Nev.    Reproduced  in  line  work  after  colored 
plate  by  J.  S.  Curtis,  Monograph  VI.,  U.  S.  Geol.  Survey. 

depth  are  considered  to  have  furnished  them. "  Eureka  was  one  of 
the  first  places  in  this  country  where  the  hypothesis  of.  replace- 
ment was  applied  to  ores  in  limestone.  The  district  is  now  far 
less  productive  than  it  was  ten  or  fifteen  years  ago.1 

1  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  32.  Rec.  W.  P.  Blake, 
"  The  Ore  Deposits  of  the  Eureka  District,  Nevada,"  M.  E.,  VI.  554.  J.  S. 
Curtis,  "Silver-lead  Ore  Deposits  of  Eureka,  Nev,,"  Monograph  VII. 9 


198  KEMP'S   ORE  DEPOSITS. 

AKIZOXA CALIFORNIA. 

2.08.30.  Some  $98,000  worth  of  lead  ores  were  shipped  from 
Arizona  in  1889,  chiefly  from  Cochise  County  (Tombstone  region) 
and  Pima  County  (Tucson  region).  They  will  be  mentioned  un- 
der "Silver."  Insignificant  amounts  are  also  afforded  by  Cali- 
fornia (about  $2000  in  1889),  mostly  from  Inyo  County.  (See 
Eleventh  Census,  Bull.  No.  80,  June  18,  1891.) 

U.  S.  Geol.  Survey.  A.  Hague,  "  Geology  of  the  Eureka  District,"  Mon- 
ograph XX.,  U.  S.  Geol.  Survey.  Abstract  in  Third  Ann.  Rep.  Director 
U.  S.  Geol.  Survey.  W.  S.  Keyes,  "Eureka  Lode  of  Eureka,  Nev.," 
M.  E.,  VI.  344.  J.  S.  Newberry,  School  of  Mines  Quarterly,  March,  1880. 
R.  W.  Raymond,  "The  Eureka-Richmond  Case,"  M.  E.,  VI.  371.  C.  D. 
Walcott,  "Paleontology  of  the  Eureka  District,"  Monograph  VIII. ,  U.  S. 
Geol.  Survey. 


CHAPTER  IX. 

SILVER  AND  GOLD.— INTRODUCTORY :  EASTERN  SILVER  MINES 

AND  THE  ROCKY  MOUNTAIN  REGION  OF  NEW  MEXICO 

AND  COLORADO. 

2.09.01.  The  two  "  precious  "  metals  are  so  generally  associ- 
ated that  they  cannot  be  separately  treated.  While  endeavoring  to 
preserve  the  distinctive  impression  given  by  examples,  it  is  practi- 
cally impossible  to  set  forth  all  the  widely  varying  phenomena  of 
the  silver-gold  veins  of  the  West  in  any  other  than  an  approxi- 
mate way.  Hence  geographical  considerations  are  placed  first,  and 
where  markedly  similar  ore  bodies  in  different  States  are  to  be 
grouped  together  cross  references  are  given.  The  following  gen- 
eral examples  have  been  made  because  their  individual  features 
are  based  on  those  geological  relations  which  are  most  vitally  con- 
cerned with  questions  of  origin. 

2.09.0*2.  Example  37.  Veins  containing  the  precious  metals 
usually  with  pyrite,  galena,  chalcopyrite,  and  less  common  sul 
phides,  sulpharsenides,  sulphantimonides,  etc.,  in  igneous  rocks. 
No  special  subdivision  is  made  on  the  character  of  the  gangue, 
which  may  be  quartz,  calcite,  barite,  fluorite,  etc.,  one  or  all.  The 
first  named  is  commonest.  A  great  and  well-defined  original  fis- 
sure, is  not  necessarily  assumed,  but  some  crack,  or  joint,  or  crushed 
strip  must  have  directed  the  ore-bearing  solutions,  which  may  have 
then  replaced  the  walls  in  large  measure.  For  other  structural 
features  see  the  discussion  of  veins  (1.05.01)  ;  compare  also  Ex- 
ample 17,  Butte,  Mont. 

Example  37a.  Replacements  more  or  less  complete  of  igneous 
dikes,  w^hich  have  usually  been  described  as  porphyry.  Compare 
Example  l7a  under  '.'  Copper "  (Gilpin  County,  Colorado),  and 
Example  20cl  (Santa  Rita,  N.  M.).  Ore  and  gangue  (where  the 
matrix  is  not 'the  dike  rock)  as  in  Example  37. 

Example  38.  Contact  deposits  between  two  kinds  of  igneous 
rock  or  between  two  different  flows.  Ore  and  gangue  as  in  Ex- 
ample 37. 


200  KEMP'S  ORE  DEPOSITS. 

Example  39.  Agglomerates  of  rounded,  eruptive  boulders, 
bombs,  etc.,  in  abandoned  volcanic  necks  or  conduits,  and  coated 
with  ores.  The  mines  of  Ouster  County,  Colorado,  are  the  only 
examples  of  ore  deposits  of  this  kind  yet  identified. 

Example  40.  Contact  deposits  between  igneous  and  sedimen- 
tary rocks.  No  subdivisions  are  made  on  the  kind  of  rocks.  Ore 
and  gangue  as  in  Example  37.  Compare  also  Example  20,  "  Ari- 
zona Copper ;"  Example  2  la,  "  Triassic  Copper;"  Example  30, 
"  Leadville  ;  "  and  Example  30^,  "  Horn  Silver  Mine." 

Example  41.  Veins  in  sedimentary  rocks,  generally  cutting  the 
bedding,  but  at  times  parallel  with  it.  Lateral  enlargements  are 
frequent.  The  ore  body  may  be  largely  due  to  replacement.  Ore 
and  gangue  as  in  Example  37. 

Example  42.  Veins  cutting  both  sedimentary  and  igneous 
rocks,  and  therefore  due  to  disturbances  after  the  intrusion  of  the 
latter.  Ore  and  gangue  as  in  Example  37. 

No  special  examples  are  made  for  metamorphic  rocks. 

2.09.03.     Silver  minerals. 

Ag.          S.         As.         Sb.         Cl. 

Native  silver 100. 

Argenite  (silver  glance),  Ag2S 87.1  12.9 

Prousite  (light  ruby  silver),  3Ag2S.As2S3 ..  65.5  19.4    15.1 

Pyrargerite  (dark  ruby  silver),  3Ag2S.Sb2S3.  59.8  17.7  22.5 

Stephanite  (brittle  silver),  5 Ag2S.Sb2S3 68 . 5  16 . 2  15.3 

Cerargerite  (horn  silver),  AgCl 75.3  24.7 

Silver  also  occurs  with  galena  (Cf.  "Lead")  and  with  tetrahe- 
drite  (Cf.  "  Copper  ").  Gold  occurs  combined  with  tellurium  in  a 
few  rare  tellurides,  mechanically  mingled  with  pyrites,  and  as  the 
uncombined  native  metal.  From  a  metallurgical  point  of  view  the 
ores  of  the  precious  metals  are  divided  into  two  classes.  1.  Those 
whose  amount  of  precious  metal  amalgamates  readily  with  mer- 
cury, and  is  thus  obtained  with  comparative  ease — the  free  milling 
ores.  2.  Those  which  require  roasting  or  some  previous  treatment 
before  amalgamation,  chlorination,  or  similar  process,  or  which 
must  be  smelted  primarily  for  lead  or  copper,  from  which  the 
precious  metals  are  afterward  extracted — the  rebellious  ores.  In 
the  subsequent  description  the  endeavor  has  been  made  to  work 
from  the  distinctively  silver  mines  to  those  of  gold  where  geo- 
graphically possible.1 

1  Ann.  Reps.  Directors  of  the  Mint.     Rec.     W.  P.  Blake,  "  The  Vari- 


SILVER  AND   GOLD.  .      201 

2.09.04.  Example  22a.     Atlantic  Border.    Already  mentioned 
(2.05.02),  the  region  is  only  of  historical  interest  as   affording  sil- 
ver, although  lately  some  attention  has  been  directed  to  Sullivan, 
Me.,  where  the  veins  have  pyrite   and  probably  stephanite,   in  a. 
quartz  gangue,  in  slates,  associated   with  granite  knobs   and  trap 
dikes  which  are  of  later  age  than  the  veins.     Some  silver  is  gener- 
ally found  in  the  galena  of  the  Eastern  States,  but  the  ores  have 
never  yet  proved  abundant  enough  to  be  important.1 

Mention  may  also  be  made  at  this  point  of  the  argentiferous 
galena  veins  along  the  Ouachita  uplift  of  Arkansas.  A  few  are 
known,  usually  with  Trenton  shales  or  slates  for  walls.  They  are 
low  grade,  and  though  once  the  basis  of  a  small  excitement,  their 
production  has  never  been  serious.  Additional  reference  to  the 
region  will  be  found  under  "Antimony."  Some  mines  of  the  lat- 
ter metal  are  stated  by  W.  P.  Jenney  to  show  low-grade,  argentif- 
erous ores  in  depth.2 

2.09.05.  Example  42.     Silver  Islet,  Lake  Superior.     A  fissure 
vein  carrying  native  silver,  argentite,  tetrahedrite,  galena,  blende, 
and  some  nickel  and  cobalt  compounds  in  a  gangue  of  calcite,  in 
flags  and  shales  of  the  Animikie  (Cambrian)   system,  and  cutting 
a  large  trap  dike,   within    which   alone    the  vein  is  productive. 
Silver  Islet  is  or  was  originally  little  more  than  a  bare  rock  some 

ous  Forms  in  which  Gold  Occurs  in  Nature,"  Pep.  Director  of  the  Mint, 
1884,  p.  573.  Rec.  Brown,  Raymond,  and  others,  1868  to  1876,  "Mineral 
Resources  West  of  the  Rocky  Mountains."  Annual.  T.  C.  Chamberlain, 
"On  the  Geological  Distribution  of  Argentiferous  Galena,"  Geol.  of  Wis., 
Vol.  IV.  Clarence  King,  "Production  of  the  Precious  Metals  in  the 
United  States,"  Second  Ann.  Rep.  Director  U.  S.  Geol.  Survey,  p.  333.  A. 
G.  Lock,  Gold,  1882.  Mineral  Resources  of  the  U.  S.;  annual  publication  of 
the  Geological  Survey.  R.  I  Murchison,  "General  View  of  the  Conditions 
under  which  Gold  is  Distributed,"  Quar.  Jour.  Geol.  Soc.,  VII.  134.  Also 
in  Siluria  and  Amer.  Jour.  Sci.,  ii.,  XVIII.  301.  J.  S.  Newberry,  "On  the 
Genesis  and  Distribution  of  Gold,"  School  of  Mines  Quarterly,  III.,  No.  1, 
and  Engineering  and  Mining  Journal,  Dec.  24  and  31,  1881,  pp.  416,  437. 
R.  Pearce,  "On  the  Ores  of  Gold,''  etc.,  Colo.  Sci.  Soc.,  III.,  p.  237.  J.  A. 
Phillips,  Ore  Deposits,  1884.  The  Mining  and  Metallurgy  of  Gold  and 
Silver,  1867.  Tenth  Census  Report  on  the  Precious  Metals. 

1  C.  %\  Kempton,  "Sketches  of  the  New  Mining  District  at  Sullivan, 
Me.,"  M.  E.,  VII.  349.     M.  E.  Wadsworth,  "Theories  of  Ore  Deposits," 
Proc.  Boston  Soc.  Nat.  Hist.,  1884,  p.  205.     Engineering  and  Mining  Jour- 
nal, May  17, 1884.     Bull.  Mus.  Comp.  Zodl,  3,  Vol.  VII.,  181. 

2  T.  B.  Comstock,  Ann.  Rep.  Geol.  Survey  of  Arkansas,  1888,  Vol.  I., 
"  Gold  and  Silver." 


202  KEMPS   ORE  DEPOSITS. 

90  feet  square,  lying  off  the  north  shore  of  Lake  Superior  just  out- 
side of  Thunder  Bay,  and  within  the  Canadian  boundaries.  The 
native  silver  was  detected  outcropping  beneath  the  water.  The 
vein  was  productive  to  a  depth  of  800  or  1000  feet,  but  below  this 
it  yielded  little.  The  trap  dike  has  usually  been  called  diorite, 
but  is  determined  to  be  norite  by  Wads  worth  (Bull.  2,  Minn. 
Geol.  Survey,  p.  92),  and  gabbro  by  Irving  (Monograph  V.,  U. 
S.  Geol.  Survey,  p.  378).  Some  $3,000,000  was  obtained  from 
the  mine,  yet  the  expenses  were  so  great  in  keeping  up  the  surface 
works  against  winter  gales  and  ice  that  but  little  profit  was 
realized.  The  vein  has  been  traced  9000  feet  but  is  nowhere  else 
productive.  Considerable  graphite  has  been  found  in  the  work- 
ings, and  some  curious  pockets  of  gas.1 

2.09.06.  Example  42.     Thunder  Bay,  Canada.     The  mainland 
near  Silver  Islet   contains  many    similar  veins.     They    have  fur- 
nished considerable  silver  as  argentite  in  a  gangue  of  quartz,  barite, 
calcite,  and-  fluorite,  and  associated  with  zincblende,  galena,  and 
pyrite.2 

THE  REGION  OF  THE  ROCKY  MOUNTAINS  AND  BLACK  HILLS. 

NEW    MEXICO. 

2.09.07.  Geology. — The  general  topography    and  geology   of 
New  Mexico  were  outlined  in  the  introduction.     Much  remains  to 
be  done  in  developing  its  geology.     The  eastern  part  belongs  to 
the   prairie  region   and  is  very  dry.     A  few  rivers,  notably    the 
Pecos  and  the  Rio  Grande,  afford  water  for  irrigation,  the  former 
of  which  is  now  being  utilized  on  a  grand  scale,  and  for  the  latter 
plans  have  been  prepared.     In  the   central  portion   many  subordi- 


1  R.  Bell,  Engineering  and  Mining  Journal,  Jan.  8  and  15,  1887.    See 
also  May  14,  1887.    W.  M.  Courtis, '"  On  Silver  Islet,"  Engineering  and 
Mining  Journal,  Dec.  21,  1873,  and  M.  E.,  V.  474.     E.  D.  Ingall,  Ann.  Rep. 
Can.   Geol.   Survey,   1887-88,   Part  II.,  p.  14.     F.A.Lowe,  "The  S.lver 
Islet  Mine  and  its  Present  Development,"  Engineering  and  Mining  Jour- 
nal, Dec.  16, 1882,  p.  321.     T.  MacFarlane,  "Silver  Islet,"  M.  E.,  VIII.  226. 
Geol.  of  Canada,  1863,  717.     Canadian  Naturalist,  Vol.  IV. ,  p.  37.    McDer- 
mott,  Engineering  and  Mining  Journal,  Vol.  XXIII.,  Nos.  4  and  5. 

2  R.  Bell,  "Silver  Mines  of  Thunder  Bay,"  Engineering  and  Mining 
Journal,  Jan.  8  and  15,  1887.     E.  D.  Ingall,  Ann.  Rep.  Can.  Survey,  1887- 
88,   Part  II.,  p.  1H.     Rec.      See  also  Engineering  and  Mining  Journal, 
May  14,  1887  ;  Feb.  18,  1888,  p.  123  ;  May  26,  1888,  p.  383. 


SILVER  AND   GOLD.  203 

nate  north  and  south  ranges  of  mountains  are  found,  which  are 
less  elevated  than  those  of  Colorado.  The  Colorado  ranges  vir- 
tually die  out  at  the  northern  boundary.  The  northwestern  por- 
tion comes  in  the  great  Colorado  Plateau,  and  has  been  quite 
fully  described  by  Captain  Dutton  (Eighth  Ann.  Rep.  Director 
IT.  S.  Geol.  Survey}.  In  numerous  localities  throughout  the 
Territory  volcanic  action  has  been  rife  and  in  places  is  but  re- 
cently extinct.  The  eastern  part  is  largely  Cretaceous,  and  also 
the  northeastern  plateau,  which  contains  much  valuable  coal.  The 
mountain  ranges  often  have  nuclei  of  Archaean  crystalline  rocks, 
with  successive  strata  of  Carboniferous,  Permian,  Triassic,  Juras- 
sic, and  Cretaceous  on  the  flanks.  The  mining  regions  are  in 
these  ranges  of  mountains.1 

2.09.08.  The  southwestern  county  is  Grant,  whose  lead-silver 
deposits  have  been  briefly  referred  to.  North  of  Silver  City  are 
quartz  veins  of  gold  and  silver  ores,  in  diabase  and  quartz  por- 
phyry (Example  37),  and  again,  west  of  Silver  City,  are  ferru- 
ginous deposits  with  chlorides  and  sulphides  of  silver  in  limestone. 
In  the  Burro  Mountains  are  silver  ores  in  limestones,  apparently 
Lower  Silurian.  The  Santa  Rita  Mountains  contain,  in  addition 
to  the  copper  (Example  20c7),  silver  and  gold  in  quartz  veins  in 


1  W.  P.  Blake,  Proc.  Bost.  Soc.  Nat.  Hist.,  1859,  Vol.  VII.,  p.  64 
"  Geology  of  the  Rocky  Mountains  in  the  Vicinity  of  Santa  Fe,"  A.  A.  A.  S., 
1859.  A.  R.  Conkling,  "Report  on  Certain  Foothills  in  Northern  New 
Mexico,"  Wheeler's  Survey,  Rep.  of  Chief  of  U.  S.  Engineers,  1877,  II.  1298. 
E.  D.  Cope,  "  Report  on  the  Geology  of  a  Part  of  New  Mexico,''  Wheeler's 
Survey,  1875  ;  Appendix  Gl.  C.  E.  Dutton,  "Mount  Taylor  and  the  Zuni 
Plateau,"  Sixth  Ann.  Rep.  U.  S.  Geol.  Survey,  pp.  111-205.  S.  F.  Emmons, 
Tenth  Census,  Vol.  XIII.  100.  O.  Loew,  "Report  on  the  Geology  and 
Mineralogy  of  Colorado  and  New  Mexico,"  Wheeler's  Survey,  1875  ;  Ap- 
pendix G2,  p.  27.  J.  Marcou,  "The  Mesozoic  Series  of  New  Mexico," 
Amer.  Geol.,  IV.  155,  216.  R.  E.  Owen  and  E.  J.  Cox,  "Report  on  the 
Mines  of  New  Mexico,"  Washington,  1865,  60  pp.,  Amer.  Jour.  Sci.,  ii., 
XL.  391.  G.  F.  Runton,  "  On  the  Volcanic  Rocks  of  New  Mexico,"  Quar. 
Jour.  Geol.  Soc.,  Vol.  VI.,  p.  251,  1850.  B.  Silliman,  Jr.,  "The  Mineral 
Regions  of  Southern  New  Mexico,"  M.  E.,  X.  434.  F.  Springer,  "Occur- 
rence of  the  Lower  Burlington  Limestone  in  New  Mexico,"  Amer.  Jour. 
Sci.,  iii.,  XXVII.  97.  J.  J.  Stevenson,  "Geological  Examinations  in 
Southern  Colorado  and  Northern  New  Mexico,"  Wheeler's  Survey,  1881. 
"  Geology  of  Galisteo  Creek,"  Amer.  Jour.  Sci.,  iii.,  XVIII.  471.  "  On  the 
Laramie  Group  of  Southern  New  Mexico,"  Amer.  Jour.  Sci.,  iii.,  XXII. 
370. 


104  KEMP'S   GEE  DEPOSITS. 

eruptive  rocks  (Example  37).  Lake  Valley,  in  Dona  Ana  County, 
has  been  mentioned  (2.08.04).  In  Lincoln  County  gold  ores  are 
reported  from  the  White  Oak  district.  The  principal  mines  of 
Socorro  County  have  been  mentioned  (Example  29),  and  the  cop- 
per in  Permian  sandstone  under  Example  21c.  There  are  other 
silver-bearing  lodes  in  the  Socorro  Mountains  near  the  town  of 
Socorro.  Henrich  has  described  (1.  c.)  a  curious  deposit  of  quartz 
carrying  gold  and  silver  (the  Slayback  Lode)  on  the  contact  be- 
tween the  older  bedded  eruptions  and  a  later  siliceous  dike  in  the 
Mogollon  range  (Example  38).  In  Santa  Fe  County  are  impor- 
tant placer  mines  (Example  44)  and  thin  veins  of  galena  in  rhyo- 
lite.  In  Bernalillo  County  are  placers  on  the  slopes  of  the  Sandia 
Mountains.  In  Colfax  County,  in  the  Rocky  Mountains,  are  other 
placers,  and  reported  gold  and  silver  mines.J 

COLORADO. 

2.09.09.  Geology. — The  eastern  portion  contains  prairies  and  is 
a  region  lacking  water.  It  consist  of  Quaternary  and  Creta- 
ceous rocks.  The  plains  rise  in  the  foothills,  which  are  chiefly  up- 
turned Jura-Triassic  and  Cretaceous  strata.  The  Paleozoic  is  rela- 
tively limited,  although  known.  It  rests  on  the  crystalline  rocks 
of  the  Archaean.  There  are  some  minor  uplifts,  running  out  at  right 
angles  to  the  Front  range,  that  divide  the  foothill  country  into 
basins,  and  are  especially  important .  in  connection  with  coal. 
Next  come  the  easterly  ranges  of  the  Rocky  Mountains,  in  linear 
north  and  south  succession.  They  consist  largely  of  dome-shaped 
peaks  of  granite,  with  great  local  developments  of  volcanic  rocks. 
To  the  west  follow  the  several  parks,  largely  consisting  of 
Mesozoic  strata.  They  are  bounded  by  ranges  again  on  the  west, 
some  of  which,  like  the  Mosquito  range  (see  under  Example  30), 
mark  great  lines  of  post-Cretaceous  upheaval,  and  are  accompanied 
by  immense  igneous  intrusions.  On  the  east  and  west  flanks  of 
the  Sawatch  range  (the  granitic  Continental  Divide)  are  Paleozoic 

1  W.  P.  Blake,  "Gold  in  New  Mexico,"  Proc.  Bost.  Soc.  Nat.  Hist., 
VII.,  p.  16,  July,  1859.  "Observations  on  the  Geology,  etc.,  near  Santa 
Fe,"  A.  A.  A.  S.,  X.  1859.  S.  F  Emmons,  Tenth  Census,  XIII.,  p.  101. 
C.  Henrich,  "The  Slayback  Lode,  New  Mexico,"  Engineering  and  Mining 
Journal,  July  13,  1889,  p.  27.  R.  E.  Owen  and  E.  T.  Cox,  Rep.  on  the 
Mines  of  New  Mexico,  Washington,  1865.  Rep.  Director  of  the  Mint,  1882, 
p.  339.  B.  Silliman,  "  Mineral  Resources  of  Southern  New  Mexico,"  M.  E., 
X.  424.  Engineering  and  Mining  Journal,  Oct.  14  and  21, 1882,  pp.  199, 212. 


SISVER  AND   GOLD.  205 

strata  in  considerable  thickness,  but  to  the  west  they  dip  under 
the  vastly  greater  development  of  Mesozoic  terranes  which  shade 
out  into  the  Colorado  Plateau.  In  northern,  central,  and  south- 
western Colorado  are  vast  developments  of  igneous  rocks  that 
have  attended  the  geological  disturbances.1 

2.09.10.  The  San  Juan  region  includes  several  counties  in 
southwestern  Colorado,  in  whole  or  in  part,  viz.:  Ouray,  Hinsdale, 
San  Juan,  Dolores,  and  La  Plata.  The  chain  of  the  San  Juan 
Mountains  consists  of  great  successive  outflows  of  eruptive  rocks, 
porphyry,  diabase,  diorite,  basalt,  etc.,  which  cover  up  the  Archfe- 
an  and  later  sedimentary  terranes,  except  in  a  few  scattered  ex- 


1  G.  L.  Cannon,  "  Quaternary  of  the  Denver  Basin/'  Proc.  Colo.  Sci. 
Soc.,  III.  48.  See  also  III.  200.  W.  Cross,  "The  Denver  Tertiary  Forma- 
tion," Amer.  Jour.  Sci.,  iii.,  XXXVII.  261.  G.  H.  Eldredge,  "On  the 
Country  about  Denver,  Colo.,"  Proc.  Colo.  Sci.  Soc.,  III.  86.  See  also  140. 
S.  F.  Emmons,  "  Orographic  Movements  in  the  Rocky  Mountains,"  Geol. 
Soc.  of  America,  I.  245-286.  F.  M.  Endlich,  "On  the  Eruptive  Rocks  of 
Colorado,"  Tenth  Ann.  Rep.,  Hayderis  Survey.  H.  Gannett,  "  Report  on 
the  Arable  and  Pasture  Lands  of  Colorado,"  Hayden's  Survey,  1876,  p.  313. 
H.  C.  Freeman,  "  The  La  Platte  Mountains,"  M.  E.,  XIII.  681.  G.  K.  Gil- 
bert, "  Colorado  Plateau  Province  as  a  Field  for  Geological  Study,"  Amer. 
Jour.  Sci.,  iii.,  XII.  16,85.  J.  D.  Hague,  Fortieth  Parallel  Survey,  Vol. 
III.,  p.  475.  F.  V.  Hayden,  Reports  of  Hay  den's  Survey,  1873, 1874,  p.  40  ; 
1875,  p.  33  ;  1876,  pp.  5,  70.  R.  C.  Hills,  "Preliminary  Notes  on  the  Erup- 
tions of  the  Spanish  Peaks,"  Proc.  Colo.  Sci.  Soc.,  III.  24,  p.  224.  "The 
Recently  Discovered  Tertiary  Beds  of  the  Huerfano  River  Basin,"  Proc. 
Colo.  Sci.  Soc.,  III.,  pp.  148,  217.  "  Jura-Trias  of  Southeastern  Colorado," 
Amer.  Jour.  Sci.,  iii.,  XXIII.,  p.  243.  A.  Lakes,  "Extinct  Volcanoes  in 
Colorado,"  Amer.  Geol.,  January,  1890,  p.  38.  Oscar  Loew,  "  Report  on  the 
Minerals  of  Colorado  and  New  Mexico,"  Wheeler's  Survey,  1875,  p.  97. 
"  Eruptive  Rocks  of  Colorado,"  Wheeler's  Survey,  1873.  C.  A.  H.  McCauley, 
"On  the  San  Juan  Region,"  Rep.  Chief  of  U.  S.  Engineers,  1878,  III.,  p. 
1753.  C.  S.  Palmer,  "On  the  Eruptive  Rocks  of  Boulder  County,"  He., 
Proc.  Colo.  Sci.  Soc.,  III.,  p.  230.  A.  C.  Peale,  "  On  the  Age  of  the 
Rocky  Mountains  in  Colorado,"  Amer.  Jour.  Sci.,  iii  ,  XIII.,  p.  172  ;  Reply 
to  the  above  by  J.  J.  Stevenson,  Amer.  Jour.  Sci.,  iii,  XIII.  297.  S.  H. 
Scudder,  "The  Tertiary  Lake  Basin  at  Florissant,"  Hayden's  Survey,  1878, 
p.  271 ;  see  also  1877.  J.  A.  Smith,  Catalogue  of  the  Principal  Minerals 
of  Colorado,  Central  City,  1870.  J.  J.  Stevenson,  "Notes  on  the  Laramie 
Group  of  Southern  Colorado,''  Amer.  Jour.  Sci.,  iii.,  XVIII.  129.  "The 
Mesozoic  Rocks  of  Southern  Colorado,"  Amer.  Geol,  III.,  p.  391.  P.  H. 
VanDiest,  "Colorado  Volcanic  Cones,"  Proc.  Colo.  Sci.  Soc.,  III.,  p.  19. 
C.  A.  White,  "  On  Northwestern  Colorado,"  Ninth  Ann.  Rep.  Director 
U.  S.  Geol.  Survey,  683-710. 


206  KEMP'S   ORE  DEPOSITS. 

posures.  Considerable  masses  of  rocks  formed  of  fracjmental 
ejectamenta  are  also  known.  All  these  are  crossed  by  immense 
vertical  veins,  largely  with  quartz  gangue,  and  containing  argen- 
tiferous minerals  of  the  usual  species,  galena,  tetrahedrite,  pyrar- 
gerite,  and  native  silver,  as  well  as  bismuth  compounds.  Gold 
has  been  quite  subordinate,  although  late  developments  near  Ouray 
have  shown  some  peculiar  and  interesting  deposits.  R.  C.  Hills, 
in  the  Proc.  Colo.  Sci.  Soc.,  1883,  traced  three  systems  of  veins. 
(1)  Silver-bearing,  narrow  (six  inches  to  three  feet),  nearly  verti- 
cal veins,  with  base  metal  ores  and  no  selvage.  (2)  Large,  strong, 
gold-bearing  veins  dipping  60°  with  selvages  and  intersecting  (1). 
(3)  Like  (l),  but  larger  and  more  persistent,  and  carrying  occa- 
sionally bismuth  and  antimonial  ores  with  gold  and  little  or  no 
silver.  T.  B.  Comstock  (M.  JK,  XV.  218)  has  classified  the  veins 
in  three  radiating  systems.  (1)  The  northwest,  with  tetrahedrite 
(freibergite).  (2)  The  east  and  west,  with  bismuth  and  less  often 
nickel  and  molybdenum.  (3)  The  northeast,  with  tellurides  and 
antimony  and  sulphur  compounds  of  the  precious  metals.  Quite 
recently  a  series  of  small  caves  near  Ouray,  in  quartzite  overlaid 
by  bituminous  shales,  have  been  found  to  contain  native  gold,  and 
have  excited  great  interest.  It  is  thought  by  Endlich  that  they 
represent  inclusions  of  shale,  now  dissolved  away,  and  that,  the 
gold  was  precipitated  on  the  walls.  If  this  view  is  correct,  they 
mark  one  of  the  very  few  illustrations  of  chamber  deposits  which 
are  known.  More  extended  mining  work  has  proved  them  to  be 
in  all  cases  connected  with  a  supply  fissure  from  which  small  lead- 
ers guide  the  miners  to  the  chambers. 

Placer  gold  mines  (Example  44)  are  quite  extensively  worked 
in  San  Miguel  County.  J.  B.  Farish  has  recently  described  the 
veins  at  Newman  Hill,  near  Rico,  in  a  valuable  paper  cited  below. 
The  lowest  formation  exposed  is  magnesian  limestone,  supposed 
to  be  Carboniferous.  It  contains  large  ore  bodies  of  low  grade, 
and  is  also,  strangely  enough,  heavily  charged  with  carbonic  acid 
gas.  Above  this  for  500  feet  are  alternating  sandstones  and 
shales,  and  then  a  narrow  stratum  of  limestone  18  to  30  inches 
thick.  This  is  followed  by  about  500  feet  additional  of  shales  and 
sandstone,  regarded  as  Carboniferous.  Fifty  feet  above  the  low- 
est limestone  a  laccolite  of  porphyrite  has  been  intruded.  Two 
sets  of  fissures  are  present — one  nearly  vertical  and  striking  north- 
east, the  second  dipping  30  to  45°  northeast  and  striking  north- 
west. The  former  are  the  richest,  are  banded  (see  Fig.  5)  and  per- 


SILVER  AND   GOLD.  207 

sistent,  being  worked  in  one  case  for  4000  feet.  The  flatter  fissures 
are  less  rich.  The  principal  ore  bodies,  however,  occur  as  hori- 
zontal enlargements  of  both  these  sets  of  veins.  Just  over  the 
thin  bed  of  limestone  mentioned  above  the  ores  have  spread  out 
into  sheets  from  20  to  40  feet  wide  and  from  a  few  inches  to  three 
feet  thick.  They  consist  of  solid  masses  of  the  common  sulphides, 
galena,  pyrite,  gray  copper,  etc.,  and  are  very  rich.  Above  them 
the  fissures  apparently  cease,  or  at  least  are  tight.  Two  hundred 
feet  down  from  them  the  vein  filling  becomes  nearly  barren,  glassy 
quartz.  These  are  most  remarkable  ore  bodies,  and  would  appear 
to  have  been  formed  by  uprising  solutions,  which  met  the  tight  place 
and  spread  sidewise,  depositing  their  minerals;  but  as  Mr.  Farish 
advances  no  explanation,  it  is  hardly  justifiable  for  others,  less 
familiar  than  himself  with  the  phenomena,  to  do  so. 

The  lead-silver  ores  of  Red  Mountain  and  Rico  have  already 
been  mentioned  (2.08.17).  Silverton  and  Ouray  are  the  principal 
towns  of  the  San  Juan.1 

2.09.11.  The  new  mining  region  of  Creede,  now  decided  to  be 
in  Saguache  County,  should  be  mentioned  in  this  connection.  It 


1  T.  B.  Comstock,  "The  Geology  and  Vein  Structure  of  Southwestern 
Colorado,"  M.  E.,  Vol.  XV.,  218  ;  also  XI.  165,  and  Engineering  and  Min- 
ing Journal,  numerous  papers  in  1885.  "Hot  Spring  Formation  in  the 
Red  Mountain  District,  Colorado,"  M.  E.,  XVII.  281.  Rec.  S.  F.  Em- 
mons,  "On  the  San  Juan  District,"  Engineering  and  Mining  Journal, 
June  9,  1883,  p.  332.  "  Structural  Relations  of  Ore  Deposits,"  M.  E.,  XVI. 
804.  Rec.  Tenth  Census,  Vol.  XIII.,  p.  60.  F.  M.  Endlich,  "Origin  of 
the  Gold  Deposits  near  Ouray,"  Engineering  and  Mining  Journal,  Oct.  19r 
1889.  "San  Juan  District,"  Hayden's  Survey,  1874,  p.  2^9.  Ibid.,  1875,. 
Bull.  III.;  Amer.  Jour.  Sci.,  iii.,  X.  58.  J.  B.  Farish,  "On  the  Ore  De- 
posits of  Newman  Hill,  near  Rico,  Colo.,"  Colo.  Sci.  Soc.,  April  4,  1892.. 
Rec.  R.  C.  Hills,  Proc.  Colo.  Sci.  Soc.,  1883.  Rec.  W.  H.  Holmes,  "  La 
Plata  District,"  Haydens  Survey,  1875;  Amer.  Jour.  Sci.,  iii.,  XIV.  420. 
M.  C.  Ihlseng,  "  Review  of  the  Mining  Interests  of  the  San  Juan  Region,'" 
Rep.  Colo.  State  School  of  Mines,  1885,  p.  27.  G.  E.  Kedzie,  "  The  Bedded 
Ore  Deposits  of  Red  Mountain  Mining  District,  Ouray  County,  Colorado,''' 
M.  E.,  XV.  570.  Rec.  G.  A.  Koenig  and  M.  Stocker,  "  Lustrous  Coal  and 
Native  Silver  in  a  Vein  in  Porphyry,  Ouray  County,  Colorado,"  M.  E., 
IX.  650.  T.  E.  Schwartz,  "The  Ore  Deposits  of  Red  Mountain,  Ouray 
County,  Colorado,"  M.  E.,  1889.  J.  J.  Stevenson,  "On. the  San  Juan," 
Wheeler's  Survey,  III.,  p.  376.  "  The  San  Juan  Region,"  Engineering  and 
Mining  Journal,  Aug.  27,  1881,  p.  136  ;  Sept.  24,  1881,  p.  201 ;  July  17, 
1880  ;  Dec.  20,  1879  ;  and  many  other  references  in  1879  and  1880.  P.  H. 
Van  Diest,  "On  the  San  Juan  District,"  Proc.  Colo.  Sci.,  January,  1886. 

>£ 


SILVER  AXD   GOLD. 


209 


is  situated  near  the  junction  of  Saguache,  Ouray,  and  Hinsdale 
counties,  and  some  ten  or  twelve  miles  from  Wagon  Wheel  Gap. 
There  is  a  great  development  of  igneous  rocks  as  well  as  of  Car- 
boniferous limestone,  but  the  veins  as  yet  developed  are  in  the 
former.  They  appear  to  be  fissure  veins  and  have  quartz,  in  large 


PIG.    52. — Geological  cross  sections  of  strata  and  veins  at  Newman  Hill, 

near  Rico,  Colo.     After  J.  B.  Parish,  Proc.  Colo.  Sci.  Soc. ,  April 

4,  1892.     See  also  Figures  5  and  6. 

part  amethyst,  with  some  manganese  minerals  as  a  gangue,  and, 
with  these,  oxidized  silver  ores.  The  mines  are  on  two  moun- 
tains, Bachelor  and  Campbell,  which  are  on  opposite  sides  of  Wil- 
low Creek  Canon.1 


1  E.  B.  Kirby,  "  The  Ore  Deposits  of  Creede  and  Their  Possibilities," 
Engineering  and  Mining  Journal,  March  19,  1892,  p.  325.  Rec.  T.  R. 
MacMechen,  "The  Ore  Deposits  of  Creede,"  Engineering  and  Mining 
Journal,  March  12,  1892,  p.  301.  Rec. 


I 


SILVER  'AXD   GOLD.  211 

2.09.12.  The  Gunnison  region  lies  on  the  western  slope  of  the 
Continental  Divide  and  embraces  both  mountains  and  plateaus. 
West  of  the  main  and  older  range  are  the  later  Elk  Mountains,  in 
which    several    mining  districts  are  located.     Aspen  has  already 
been  mentioned,  and  the  long  series  of  ore  bodies  in  the  Carbonif- 
erous limestones.     The  other  principal  districts  are  Independence, 
Ruby,  Gothic,  Pitkin,  and  Tin  Cup.     The  ores  at    Independence 
are  sulphides  with  silver,  in  the  Archaean  granite  rocks.     In  the  Tin 
Cup  district  the  Gold  Cup  mine  is  in  a  black  limestone   and  con- 
tains argentiferous  cerussite  and  copper  oxide.     In  the  Ruby  dis- 
trict the  ores  are  in  the  Cretaceous  rocks,  and  in  the  Forest  Queen 
they  are  ruby  silver  and  arsenopyrite,  partly  replacing  a  porphyry 
dike.     On  Copper  Creek,  near  Gothic,  a  series   of  nearly  vertical 
fissures  traverse  eruptive  diorite.     They  contain  sulphide  of  silver 
and  native  silver.     The  Sylvanite  is  one  of  the  principal  mines.1 

2.09.13.  Eagle  County.     The  lead-silver  mines  of  Red  Cliff 
have  already  been  mentioned  (Example  30c),  and  also  the  under- 
lying gold  deposits.     The  Homestake   mine,  northwest  of  Lead- 
ville,  over  toward  Red  Cliff,  is  on  a  vein  of  galena  in  granite,  and 
was  one  of  the  first  openings  made  in  the  region.2 

2.09.14.  Summit  County.    The  Ten  Mile  district,  which  is  the 
principal  one, has  been  mentioned  under  Example  30«.     The  Pride 
of  the  West  Tnine,  on  Jacque  Mountain,  is  peculiar,  being    on  a 
quartz  porphyry  dike  which  is  partly  replaced  by  ferruginous  quartz 
and  barite.     Lake  County,  containing  Leadville,  has  been  treated 
under  Example  30.     Mention  should  also  be  made  of  the  placer 
deposits  in  California  Gulch,  which  first  attracted  prospectors  to 
the  region  in  1860.     In  its  eastern  part  Summit  County  borders  on 
Clear  Creek  County,  and  at  Argentine  are  some  veins  related  to 
those  of  the  latter.     They  are  high  up  on  Mount  McClellan,  and 
are  remarkable  for  the  veins  of  ice  that  are  found  in  them.3 

1  F.  Amelung,  *'  Sheep  Mountain  Mices,  Gunnison  C  unty,"  Engineer- 
ing and  Mining  Journal,  Aug.  28,  1886,  p.  149.     F.  M.  C  iadwick,  "The 
Tin  Cup  Mines,  Gunnison  Count}',  Colorado,''  Engineering  and  Mining 
Journal,  Jan.  1,  1881,  p.  4.     See  also  Example  I2d  for  iron  mine-. 

2  Guiterman,  "  On  the  Gold  Deposits  of  Red  Cliff,"  Proc.  Colo.  Sci.  Soc., 
1890.     "  On  the  Battle  Mountain  Quartzite  Mines,"  Mining  Industry,  Den- 
ver, Jan.  10,  1890,  p.  28.     E.  E.  Olcott,  "Battle  Mountain  Mining  District, 
Eagle  County,"  Engineering  and  Mining  Journal,  June  11  and  18,  1887, 
pp.  417,  436 ;  May  21,  1892.     G.  C.  Tilden,   "  Mining  Notes  from  Eagle 
County,"  Ann.  Rep.  Colo.  State  School  of  Mines,  1886,  p.  129. 

3  E.  L.  Berthoud,  "Oa  Rifts  of  Ice  in  t\w  Rocks  near  the  Summit  of 
Mount  McClellan,"  etc.,  Amer.  Jour.  Sci.,  iii.,  II.  108. 


212  KEMP'S   GEE  DEPOSITS. 

2.09.15.  Park  County,   which   lies  east  of    Lake   County  and 
embraces  the  South  Park,  has  some  mines  on  the  eastern  slope  of 
the  Mosquito  range,  and  in  the  Colorado  range,  to  the  northwest. 
The  latter  are  similar  in  their  contents  to  the  Georgetown  silver 
ores,  mentioned  under  Clear  Creek  County,  but  the    former  are 
bodies  of  argentiferous  galena  and  its  alteration  products  in  lime- 
stone and  quartzite.    Pyrite  is  also  abundant,  and  at  times  a  gangue 
of  barite  appears.    The  mines  are  in  the  sedimentary  series,  resting 
on    the   granite  of  the  Mosquito    range,  and  are    pierced  by  por- 
phyry instrusions,  as  at  Leadville.     The  placer  deposits  at  Fair- 
play  deserve  mention,  as  it  was  from  these  that  the  prospectors 
spread  over  the  divide  to  the  site  of  Leadville  in  I860.1 

2.09.16.  Chaffee  County,  on  the  south,  contains  the  iron  mines 
referred  to  under  Example  12d.    There  are  some  other  gold-bearing 
veins  near  Granite  and  Buena  Vista.     The  lead-silver  deposits  of 
the    Monarch    district    are    mentioned    under    Example    30ft.      In 
Huerfano  County,  in   the   Spanish  Peaks,    veins   of  galena,  gray 
copper,  etc.,  are  worked  to  some  extent.2 

2.09.17.  Rio  Grande   County.     In  the  Summit  district  are  a 
number  of  rich  gold  mines,  of  which  the  Little  Annie  is  the  best 
known.     The  gold  occurs  in  the  native  state,  in  quartz  on  the  con- 
tact between  a  rhyolite  and  trachyte  breccia  and  andesite.    The  de- 
posits are  thought  by  R.  C.  Hills  to  be  due  to  a  silicification  of  the 
rhyolite  along  those  lines,  probably  by  the  sulphuric  acid,  which 
brought  the  gold.     Then  the  rocks  were   folded.     Oxidation  and 
impoverishment  of  the  upper  parts    followed,  forming  bonanzas 
below.      The  paper  has  a  very  important  bearing  on  the  formation 
of  many  replacements.3 

2.09.18.  Conejos  County.     Some  deposits   of  ruby  silver  ores 
have  recently  been   developed  in  this   county,  near  the   town  of 
Platoro.     The  county  lies  near  the  middle  of  the  southern  tier. 

2.09.19.  Custer  County  affords   some  of  the  most  interesting 
deposits  in  the  West.     Rosita  and  Silver   Cliff  are  the  principal 
towns  and  are  situated  in  the  Wet  Mountain  Valley,  between  the 
Colorado  range  on   the  north  and   the   Sangre  de  Cristo  on   the 


1  J.  L.  Jernegan,  "Whale  Lode  of  Park  County,"  M.  E.,  III.  352. 

2  R.  C.  Hills,  "On  the  Eruption  of  the  Spanish  Peaks,"  Proc.  Colo. 
Sci.  Soc.,  III.,  pp.  24,  224. 

8  R.  C.  Hills,. Proc.  Colo.  Sci.  Soc.,  March,  1883.    Abstract  by  S.  F. 
Emmons  in  the  Engineering  and  Mining  Journal,  June  9,  1883,  p.  332. 


SILVER  AND    GOLD.  213 

south.  At  Silver  Cliff  an  outbreak  of  pinkish  rhyolite  occurs,  im- 
pregnated with  silver  chloride.  It  affords  a  free-milling  although 
low-grade  ore.  This  forms  a  unique  deposit.  There  is  a  great 
thickness  of  tuffs  beneath  it,  as  shown  in  the  Geyser  mine,  and 
some  remarkable  forms  of  spherulitic  crystallizations. 

2.09.20.  Example  39.     Bull  Domingo  and  Bassick.     The  first 
named  is  two  miles  north  of  Silver  Cliff,  and  the  latter  seven  miles 
east,  near  Rosita.     The  Bull  Domingo  is  in  Archaean,  hornblende 
gneiss,  and  consists  of  what  appear  to  be  pebbles  or  boulders  of  the 
wall  rock,  which  are  coated  with  argentiferous  galena  and  an  out- 
er shell  of  quartz.     The  ore  body  is  40  to   60   feet  across.     The 
Bassick  is  in  andesite,  and  likewise  consists  of  what   appear  to  be 
boulders  and  pebbles  of  the  country  rock,  coated  by  concentric 
shells  of  rich  ores,  and  in  an  elliptical  chimney  20  to  100  feet  across. 
The  first  coat  is  a  mixture  of  lead,  antimony,  and  zinc   sulphides, 
and  is  always  present.     A  second,  somewhat  similar,  but  of  lighter 
color  and  richer  in  lead  and  the  precious  metals,  is  sometimes  seen. 
A  third  is  chiefly  zincblende,  rich  in  silver  and  gold,  and    is  the 
largest  of  all.     A   fourth,  of  chalcopyrite,  sometimes  occurs,   and 
lastly  a  fifth,  of  pyrite.     Various  other  minerals   are  found,  andr 
curiously   enough,   carbonized  wood   on    the    outer   limits.     Both, 
these  deposits  have  been  thought  to  be  the  tubes  of  geysers,  in 
which  boulders  have  been  tossed  about,  rounded,   and  finally  ce- 
mented together.     Mr.  Emmons  has  argued  against  this  view,  and 
in  a  forthcoming  monograph  will  present  the  results   of  extended 
study.     A  brief  account  of  these  results  has,   however,  been  pub- 
lished by  Dr.  Whitman  Cross.     The  region  is  shown  to  be  one 
containing  numerous,  although    not    always    large,    volcanic    out- 
breaks.    One    of   them  furnished  the  sheet  of  rhyolite  at  Silver 
Cliff,  while  others^had  for  their  conduits  the  chimneys  of  the  Bull 
Domingo  and  the  Bajssick.     The  ore  bodies  thus  occur  in  volcanic 
necks,  and  make  a  ne\Kform  for  the  science. 

2.09.21.  Humboldt-P^cahontas.     These  mines  are  near  Rosita 
on  fissure  veins  in  andesite,  but  of  a  different  flow  and  kind  from 
the  walls  of  the  Bassick.     They  are  filled  with  gray   copper  and 
chalcopyrite,  in  a  barite  gangue.     Other  mines  of  less  importance 
occur  in  the  district,  but  the  three  above  cited  are  given  prom- 
inence because  of  their  own   intrinsic  interest  and  because  they 
have  often  been  referred  to  in  discussions  about  the  origin  of  ores.1 

1  R.  N.  Clark,  "  Humboldt-Pocahontas  Vein,"  M.  E.,  VII,  21.     "  Sil- 


214  KEMP'S    ORE  DEPOSITS. 

2.09.22.  Gilpin    County    has    already    been    mentioned  under 
"  Copper  "  (2.04.08).     The  general  geology  of  the  veins  is  much  like 
that    of  Clear  Creek,  although    the  ores  are  quite  different.     R. 
Pearce  has  shown  the  existence  of  bismuth  in  the   ore,   and  gives 
reasons  for  believing  that  the  gold  is   in    combination   with   it. 
Clear  Creek  County  contains  veins  on   a  great  series  of  jointing 
planes  in  gneiss  (granite),  and  in   large  part  replacements  of  the 
wall.     Others  are  replacements  of  porphyry  dikes  or  of  pegmatite 
segregations.    The  ores  are  chiefly  galena,  tetrahedrite,  zincblende, 
and  pyrite,  and  the  gangue  is  the  wall  rock.     The  curious  decrease 
of  value  in  depth  of  a  series  of  parallel  veins  in  Mount  Marshall  was 
referred  to  (1.05.05).    Georgetown  is  the  principal  town  and  mining 
center.     Others  of  importance  are  Idaho  Springs  and  Silver  Plume.1 

2.08.23.  Boulder  County  contains  veins  along  joints  or  faulting 
planes  in  gneiss,  or  granite,  or  associated  with  porphyry  dikes,  or 
pegmatite  segregations,  and  carrying  tellurides    of   the  precious 
metals  more  or  less  as  impregnations  of  the   country  rock.     The 
prevalent  country  rock  is  called    by    Emmons    a   granite-gneiss. 
Van  Diest  distinguishes  four  successive  terranes  of  massive  and 
schistose  rocks  along  three  principal  axes  and  two  side  ones,  and 
states  that  the  mines  are  on  the  sides  of  the  folds.      The   country 
is  very  generally  pierced  by  porphyry  dikes,  with  which  the  ore 
bodies  are  often  associated.     A  large  number  of  species  of  tellu- 
ride  minerals  have  been  determined  from  the  region,  especially  by 
the  late  Dr.  Genth  of  Philadelphia.     The  mines  afford  very  rich 
ores,  somewhat  irregularly  distributed.2 


ver  Cliff,  Colorado,"  Engineering  and  Mining  Journal,  Nov.  2,  1878,  p. 
314.  W.  Cross,  "  Geology  of  the  Rosita  Hills,"  Proc.  Colo.  Sci.  Soc.,  1890, 
p.  269.  Rec.  S.  F.  Emmons,  "The  Genesis  of  Certain  Ore  Deposits," 
M.  E.,  XV.  146.  Tenth  Census,  Vol.  XIII.,  p.  80.  L.  C.  Gray  bill,  "  On  the 
Peculiar  Features  of  the  Bassick  Mine,"  M.  E.,  XL,  p.  110;  Engineering 
and  Mining  Journal,  Oct.  28, 1882,  p.  226.  Rec.  O.  Loew  and  A.  R.  Conk- 
ling,  "Rosita  and  Vicinity,"  Wheeler's  Survey,  1876,  p.  48.  See  also  Ste- 
venson in  the  Report  for  1873. 

1  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII. ,  p.  70.  Rec.  F.  M.  End- 
lich,  Hayden's  Survey,  1873,  p.  293 ;  1876,  p.  117.  P.  Fraser,  Hayden's 
Survey,  1869,  p.  201.  J.  D.  Hague,  Fortieth  Parallel  Survey,  Vol.  III.,  p. 
589.  Rec.  R.  Pearce,  Proc.  Colo.  Sci.  Soc.,  Vol.  III.,  pp.  71,  210.  "  The 
Association  of  Gold  with  Other  Metals,"  M.  E.,  1890.  J.  J.  Stevenson, 
Wheeler's  Survey,  Vol.  III.,  p.  351.  F  L.  Vinton,  "  The  Georgetown  (Colo.) 
Mines,"  Engineering  and  Mining  Journal,  Sept.  13,  1879,  p.  184. 

8  A.  A.  Eilers,  "  A  New  Occurrence  of  the  Telluride  of  Gold  and  Sil- 


SILVER  AND   GOLD.  215 

2.09.24.     The  resources  of  the  remaining  counties  of  Colorado 
are  chiefly  in  coal. 

very'  Jf.  E.,  Vol.  I.,  p.  16.  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  64. 
J.  B.  Farish,  "Interesting  Veins  Phenomena  in  Boulder  County,  Colo- 
rado," If.  E.,  September,  1890.  F.  A.  Genth,  "On  Tellurides,"  Amer. 
Jour.  Sci.,  ii.,  XLV,  p.  305,  and  other  papers  in  the  same  journal.  C.  S. 
Palmer,  "Eruptive  Rocks  of  Boulder  and  Adjoining  Counties,"  Proc.  Colo. 
Sci.  Soc.,  Vol.  III.,  p.  230.  P.  H.  Van  Diest,  "The  Mineral  Resources  of 
Boulder  County,"  Ann.  Rep.  Colo.  State  School  of  Mines,  1886,  p.  25. 


CHAPTER  X. 

SILVER  AND  GOLD,   CONTINUED.— ROCKY  MOUNTAIN  REGION, 
WYOMING,  THE  BLACK  HILLS,  MONTANA,  AND  IDAHO. 

WYOMING. 

2.10.01.  Geology.  —  The  southeastern    part    of   Wyoming    is 
in   the   Prairie   region,    the   southwestern   in    the   Plateau.     The 
Rocky    Mountains    shade  out  more  or  less  on  leaving  Colorado, 
but   are    again  strongly   developed  in  northern  Wyoming.     The 
northwestern  portion   contains  the  great  volcanic  district   of  the 
National  Park,  and  the  northeastern,  a  part  of  the  Black  Hills. 
The  Cretaceous  and  Tertiary  strata  chiefly  form  the  plains  and 
plateaus.     Granite  and    gneiss  constitute  the    central    portion   of 
some  of  the  greater  ranges.     Paleozoic  rocks  are  very  subordinate. 
The  resources  in  precious  metals  are  small,  consisting  chiefly  of 
gold  in  quartz  veins  in  the  gneisses,  schists,  and  granites  of  Still- 
water  County.     The  great  mineral  wealth  of  the  State  is  in  coal. 
The  iron  mines  have  already  been  mentioned  (2.03.09),  and  the 
copper  (2.04.27).1 

THE    BLACK    HILLS. 

2.10.02.  Geology. — The  Black  Hills  lie  mostly  in  South  Da- 
kota.    They    consist    of   a    somewhat    elliptical    core    of    granite 
and    metamorphic    rocks,    with    a   north    and  south  axis,  and  on 
these  are  laid  down  successive  strata  of    Cambrian,    Carbonifer- 

1  H.  M.  Chance,  "Resources  of  the  Black  Hills  and  Big  Horn  Coun- 
try, Wyoming,"  M.  E.,  XIX.,  p.  49.  T.  B.  Comstock,  "On  the  Geology 
of  Western  Wyoming,"  Amer.  Jour.  Sci.,  iii.,  VI.  426.  S.  F.  Emmons, 
Tenth  Census,  Vol.  XIII. ,  p.  86.  F.  M.  Endlich,  "The  Sweetwater  Dis- 
trict," Hayderfs  Survey,  1877,  p.  5  ;  "  Wind  River  Range  Gold  Washings," 
p.  64.  A.  Hague,  "  Geological  History  of  the  Yellowstone  National  Park," 
M.  E.,  XVI.  783.  See  also  F.  V.  Hayden,  Amer.  Jour.  Sci.,  iii.,  III.  105, 
161.  F.  V.  Hayden,  Rep.  for  1870-72,  p.  13;  also  Amer.  Jour.  Sci.,i\., 
XXXI.  229.  A.  C.  Peale,  "  Report  on  the  Geology  of  the  Green  River  Dis- 
trict," Hayden's  Survey,  1877,  p.  511.  Raymond's  Statistics  West  of  the 
Rocky  Mountains. 


SILVER  AND    GOLD,    CONTINUED. 


21' 


ous,  Jura-Trias,  and  Cretaceous  rocks.  There  are  some  igneous 
intrusions.  The  principal  product  of  the  Black  Hills  is  gold. 
The  lead-silver  deposits  have  already  been  described  (2.08.18),  and 
the  tin,  mica,  etc.,  will  be  mentioned  later.1 

2.10.03.  The  gold  occurs  in  placers  of  Quaternary  and  recent 
age,  as  well  as  in  Potsdam  sandstones,  which  are  old  shore  beaches 
now  hardened  to  rock  ;  in  pyritous  beds  in  schistose  rocks,  and  in 
segregated  quartz  veins.  The  Quaternary  and  recent  placers  are 
the  usual  gravels,  which  are  more  fully  described  under  "  Cali- 
fornia." The  Potsdam  sandstone  is  an  extremely  interesting  de- 
posit. It  has  resulted  from  the  wearing  action  of  the  waves  of 
the  Potsdam  ocean  on  the  Archaean  schists.  The  Potsdam  also 
carries  other  deposits  in  the  vicinity  of  porphyry  sheets  and  dikes, 


3    4 


FIG.  54.— Geological  section  of  the  Black  Hills.    After  Henry  Neivton 
Report  on  the  Black  Hills,  p.  206. 

1.  Schists.    2.  Granite.    3.  Potsdam  sandstone.    4.  Carboniferous.     5,  6.  Jura-Trias. 

7.  Cretaceous. 

which  consist  of  auriferous  pyrite,  sometimes  oxidized.  This  has 
replaced  the  original  calcareous  cement  of  the  quartzite.  The 
pyritous  beds  are  in  a  great  impregnation  zone  2000  feet  broad 
(Carpenter),  of  slates  and  schists,  with  portions  especially  rich  in 
auriferous  pyrites.  They  occur  near  the  town  of  Lead  City,  not 
far  from  Deadwood,  in  the  northern  hills.  The  deposits  present 
many  analogies  with  Example  16,  and  also  are  like  fahlbamls 
(1.06.10).  The  ore  is  not  high  grade,  running  $3  to  $4  per  ton, 
but  it  is  treated  at  great  profit  by  mining  it  in  enormous  quanti- 
ties. There  are  also  many  so-called  segregated  quartz  veins  in  the 

1  F.  R.  Carpenter^  "Ore  Deposits  in  the  Black  Hills,"  M.  E.,  XVII. 
870.  Prelim.  Rep.  on  the  Geol  of  the  Black  Hills,  Rapid  City,  So.  Dak., 
1888.  W.  O.  Crosby,  "  Geology  of  the  Black  Hills,"  Bost.  Soc.  Nat.  Hist., 
XXIII.,  p.  89.  Newton  and  Jenney,  Report  on  the  Black  Hills,  Washing- 
ton, 1880.  C.  R.  Van  Hise,  "  The  Pre-Cambrian  Rocks  of  the  Black  Hills," 
Bull.  Geol.  Soc.  Amer.,  I.  203-244.  N.  H.  Winchell,  "  Report  on  the  Black 
Hills,"  Rep.  Chief  of  U.  S.  Engineers,  1874,  Part  II.,  p.  630. 


218  KEMPS    ORE  DEPOSITS. 

schists  and  slates.  These  are  lenticular  masses  of  limited  extent, 
horizontally  and  below,  somewhat  like  a  magnetite  lens  (Example 
12)  in  shape,  and  carrying  a  small  amount  of  gold  with  little  or 
no  pyrites.1 

MONTANA. 

2.10.04.  Geology. — The  eastern  part  of  the  State  belongs  to 
the  Prairie  region,  which  is,  however,  in  portions  greatly  scarred 
by  erosion,  forming  the  so-called  Bad  Lands.  The  approaches  to 
the  Rocky  Mountains  are  not  abrupt  and  sudden  as  in  Colorado, 
but  are  marked  by  numbers  of  outlying  ranges  of  both  eruptive 
and  sedimentary  rocks.  The  chain  of  the  Rockies  takes  a  north- 
westerly trend  in  Wyoming,  and  so  continues  across  Montana.  It 
is  rather  the  prolongation  of  the  Wasatch  than  of  the  Colorado 
Mountains,  whose  strike  is  for  the  Black  Hills.  The  character  of 
the  ranges  is  also  very  different.  They  are  less  elevated  and  have 
broad  and  well-watered  valleys  between,  that  admit  of  considera- 
ble agriculture.  Geologically  the  country  is  in  marked  contrast 
with  Colorado.  "While  in  the  latter  the  Paleozoic  is  feebly  de- 
veloped, in  the  former  it  reaches  great  thickness.  In  the  eastern 
ranges  W.  M.  Davis  gives  Lower  Cambrian  10,000  to  15,000  feet; 
Silurian  and  Devonian,  not  yet  recognized  ;  Carboniferous  lime- 
stones, 3500  feet;  Trias,  not  definitely  recognized;  Jurassic 
and  Cretaceous  sandstones,  shales,  and  thin  limestones,  15,000 
feet.  This  more  closely  resembles  the  Wasatch  and  Great  Basin 
sections  (see  2.08.29,  and  2.11.01).  Much  granite  of  a  basic  or 
dioritic  character  is  present  (Example  17),  and  great  develop- 
ments of  eruptive  rocks  of  extremely  interesting  character.  No 
more  interesting  field  for  geological  work  awaits  the  investigator.2 

1  A.  J.  Bowie,  "Notes  on  Gold  Mill  Construction,"  M.  E.,  X.  1881. 
W.  B.  Devereux,  "The  Occurrence  of  Gold  in  the  Potsdam  Formation," 
M.  E.,  465  ;  Engineering  and  Mining  Journal,  Dec.  23,  1882,  p.  334.     H. 
O.  Hofman,  "Gold  Mining  in  the  Black  Hills,"  M.  E.,  XVII.  498  ;  also  in 
preliminary  report  cited  under  Carpenter,  under  Geology. 

2  S.  Calvin,  "Iron  Butte  :  Some  Preliminary  Notes,"  Amer.    Geol., 
IV.  95.     G.  E.  Culver,  "A  Little  Known  Region  of  Northwestern  Mon- 
tana," Wis.  Acad.,  Dec.  30,  1891.     W.  M.  Davis,  "The  Relation  of  the 
Coal  of  Montana  to  the  Older  Rocks,"  Tenth  Census,  Vol.  XV.,  p.  697. 
Rec.    J.  Eccles,  "  On  the  Mode  of  Occurrence  of  Some  of  the  Volcanic 
Rocks  of  Montana,"   Quar.  Jour.   Geol.  Sci.,  XXXVII.  399.     G.    H.  El- 
dridge,  "Montana  Coal  Fields,"  Tenth  Census,  Vol.  XV.,  p.  739.     S.  F. 
Emmons,  Tenth  Census,  Vol.  XIII.,  97.     Rec.     Hayden's  Survey,  Ann. 


SILVER  AND   GOLD,   CONTINUED.  219 

2.10.05.  Montana  took  the  lead  of  all  the  States   in  1887  in 
the  production  of  silver,  was  second  in  gold,  and  first  in  the  total 
production  of  the  two.     It  is  now  second.     In  its  mineral  wealth 
it  yields  to  no  other  State  in  the  Union.     The  mining  districts  are 
mostly  in  the    western  central    and   western  portions.     Develop- 
ments have  progressed  so  rapidly  that  all  the  desirable   data  are 
not  available. 

2.10.06.  Madison  County.     Veins  in  gneiss  containing  galena 
and   pyrite   in   a  quartz  gangue.     Virginia  City   is  the   principal 
town,  and  the  veins  are  north  of  it  in  the  northern  part   of  the 
county.1 

2.10.07.  Beaverhead  County.    Near  Bannack  City  quartz  veins 
with  auriferous  pyrite  on  the  contact  between  the  limestone  and 
so-called   granite.       At    Glendale,    in    the    northern    part    of   the 
county,  are   the    Hecla    mines,  referred    to   under  "  Lead-silver " 
(Example    32).      Auriferous   quartz    veins    are    reported    farther 
north.2 

2.10.08.  Jefferson  County.     This  county  contains  ore  bodies 
chiefly  auriferous  quartz,  in  gneiss,  porphyry,  or  limestone.     The 


Rep.,  1871-72.  W.  S.  Keyes,  in  Brown's  first  report  on  mineral  resources, 
etc.,  last  part,  Amer.  Jour.  Sci., II.  46,  431.  Rec.  W.  Lindgren,  "Eruptive 
Rocks,"  Tenth  Census,  Vol.  XV.,  p.  719,  forming  Appendix  B  of  Davis's 
first  paper.  See  also  Proc.  Cal.Ac.ad  Sci.,  Second  Series,  Vol.  III.,  p.  39.  J. 
S.  Newberry,  "Notes  on  the  Surface  Geology  of  the  Country  bordering  on 
the  Northern  Pacific  Railroad,"  Annals  N.  Y.  Acad.  Sci.,  Vol.  III.  242; 
Amer.  Jour.  Sci.,  iii.,  XXX.  337.  "  The  Great  Falls  Coal  Fields,"  in  Geol. 
Notes,  School  of  Mines  Quarterly,  VIII.  327.  F.  Rutley,  "Microscopic 
Character  of  the  Vitreous  Rocks  of  Montana,"  Quar.  Jour.  Geol.  Sci., 
XXXVII.  391.  See  Eccles,  above.  W.  H.  Weed,  "The  Cinnabar  and 
Bozeman  Coal  Fields  of  Montana,"  Bull.  Geol.  Soc.  Amer.,  II.  349-364. 
Engineering  and  Mining  Journal,  May  14  and  21,  1892.  "Montana  Coal 
Fields,"  Bull.  Geol.  Soc.  Amer.,  III.  301-330.  C.  A.  White,  "Existence  of 
a  Deposit  in  Northwestern  Montana  and  Northeastern  Dakota  that  is  Pos- 
sibly Equivalent  with  the  Green  River  Group,"  Amer.  Jour.  Sci.,  iii., 
XXV.  411.  R.  P.  Whitfield,  "List  of  Fossils  from  Central  Montana," 
Tenth  Census,  Vol.  XV.,  p.  712  ;  Appendix  A  to  Davis's  paper.  J.  E. 
Wolff,  "  Notes  on  the  Petrography  of  the  Crazy  Mountains,"  etc.,  North- 
ern Trans.  Survey.  "  Geology  of  the  Crazy  Mountains,"  Bull.  Geol.  Soc. 
Amer.,  III.  445.  H.  Wood,  "Flathead  Coal  Basin,"  Engineering  and 
Mining  Journal,  July  16,  1892,  p.  57.  H.  R.  Wood,  "Mineral  Zones  in 
Montana,"  Engineering  and  Mining  Journal,  Sept.  24,  1892,  p.  292. 

1  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  97. 

2  Ibid. 


220 


KEMP'S   ORE  DEPOSITS. 


lead-silver  mines  near  Wickes  have  been  referred  to.  (Example 
33.)  Red  Mountain  lies  at  the  head  of  a  valley  like  Wickes  and 
contains  many  narrow  argentiferous  veins.  A  concentrator  was 
at  work  on  them  in  1892.1 

2.10.09.  Silver  Bow  County.  The  copper  mines  and  the  gen- 
eral geology  of  the  Butte  City  region  were  referred  to  under 
"Copper"  (Example  17).  In  the  basic  granite,  and  north  of  the 
copper  zone,  is  a  belt  carrying  sulphides  of  silver,  lead,  zinc,  and 
iron  in  a  siliceous  gangue,  but  abundantly  associated  with  manga- 
nese compounds  of  various  sorts,  especially  rhodochrosite. 

No  manganese  is  known  in  the  copper  belt,  nor  any  copper  in 
the  silver  belt — most  striking  phenomena  in  veins  in  the  same  wall 


•fllilr 

12845  6  780 

FIG.  55. — Cross  section  of  vein  at  the  Alice  mine,  Butte,  Mont.    The  width 
of  vein  is  40  feet.    After  W.  P.  Blake,  M.  E.,  XVI. ,  p.  72. 

1.  Granite  country.  2.  Softened  granite  with  small  veins.  3.  Clay  wall  with  decom- 
posed granite.  4.  Quartz,  broken  and  seamed.  5.  Clay  and  decomposed  granite.  6.  Quartz 
and  manganese  spar— "  curly  ore."  7.  Quartz  and  ore— "hard  vein."  8.  Soft  granite 
with  veinlets.  9.  Dark-colored,  hard  granite  of  the  hanging-wall  country. 

rock.  The  line  of  outcrop  has  a  crescentic  sweep,  and  it  was 
therefore  called  by  J.  E.  Clayton  the  Rainbow  Lode.  It  includes 
from  west  to  northeast  six  claims,  all  but  two  of  which  are  con- 
trolled by  the  Alice  Company.  There  are  as  many  as  four  dis- 
tinct veins  present  in  the  Magna  Charta.  All  the  mines  show 
that  the  ore  and  gangue  have  replaced  the  granite  along  a  shat- 
tered strip,  for  cross  sections  exhibit  alternations  of  quartz  with 
ore,  rhodochrosite,  crushed  wall  rock,  residual  clay,  occasional 
horses  of  granite,  etc.  In  the  more  siliceous  granite  west  of  the 
butte  is  another  silver  belt  with  the  same  ores  as  in  the  Rainbow 


1  S.  F.  Emmons,  Tenth  Census,  Vol.  XIII.,  p.  97.     J.  S.  Newberry, 
"  On  R.  d  Mountain,"  Annals  N.  Y.  Acad.  Sci.,  III.,  p.  251. 


SILVER  AND   GOLD,   CONTINUED.  221 

Lode  and  likewise  having  manganese  minerals  associated.  The  Blue- 
bird is  the  principal  mine.  The  manganif  erous  outcrop  was  a  notable 
feature  in  the  landscape,  and  exhibited  a  broad,  rusty-black  belt, 
not  rich  at  the  surface,  but  only  showing  the  silver  in  depth.  Like  the 
veins  in  the  basic  granite,  these  were  also  formed  by  replacement  of 
the  rock  along  a  shattered  strip.  Placer  mines  were  early  worked  near 
Butte  and  led  to  the  location  of  the  deep  mines.  They  are  still  pro- 
ductive and  are  again  referred  to  under  "Auriferous  Gravels."1 

2.10.10.  Deer  Lodge  County.     Placer  deposits  are  numerous 
along  the  Deer   Lodge   River,  and    auriferous   quartz    veins    are 
known,  but  the  greatest  mine  is  the  Granite  Mountain,  a  source 
of  very    handsome  returns.     This  is  in  the  southern  part  of  the 
county,  nea;*  Phillipsburg,  and  is  a  fissure  vein  in  granite,  prin- 
cipally with  silver  ores,  although  affording  considerable  gold.     On 
the  same  vein  is  the  Bimetallic.     Farther  west  sedimentary  rocks 
come  in,  much  metamorphosed  by  contact  with  the  later  irrup- 
tive   granite.     On  the  edge  of  the  county,  and  not  far  from  the 
Drumlummon  group  of  veins,  later  mentioned,  are  the  veins  of  the 
Bald  Butte  Company,  in  slates  and  intrusive  diorite.     A  number 
of  other  veins  are  in  the  same  general  region.2 

2.10.11.  Lewis  and    Clarke  County.     The  placer  mines,  near 
Helena  (in  Last  Chance  and  Prickly  Pear  gulches),  were  the  first 
in   the   county  to    attract  attention.      They  were    found   by  the 
prospectors,  who  spread  through  the  Rocky  Mountains  as  the  Cali- 
fornia gold  diggings  gave  out.     Since  then  many  auriferous  quartz 
veins   in  granite   and  slates  have  been  developed.     Some  twenty 


1  W.  P.  Blake,  ''Silver  Mining  and  Milling  at  Butte,  Mont.."  M.  E., 
XVI.  38.     "Rainbow  Lode,  Butte,  Mont.,"  M.  E.,  XVI.  65.     Rec.     S.  F. 
Emmons,  "  Notes  on  the  Geology  of  Butte,  Mont.,"  M.  E.,  XVI.  49.     Rec. 
Richard  Pearce,  "The  Associations  of  Minerals  in  the Gagnon  Vein, Butte 
City,"  M.  E.,  XVI.  62.     E.  D.  Peters,  Mineral  Resources  of  U.  S.,  1883-84, 
p.  374.     E.  G.  Salisbury,  "  Placer  Mining  in  Montana,"  Engineering  and 
Mining  Journal,  Sept.   3,  1887,  p.  167.    Rec.     ''Silver  Mines  of  Butte, 
Mont.,"  Ibid.,  April  18, 1885,  p.  261.     Williams  and  Peters  on  Butte,  Mont., 
Engineering  and  Mining  Journal,  March  28,  1885,  p.  208. 

2  H.  M.  Beadle,  "  The  Condition  of  the  Mining  Industry  in  Montana 
in  1892,"  Engineering  and  Mining  Journal,  Feb.  11,  1893,  p.  123.    G.  W. 
Goodale  and  W.  A.  Ackers,  "Concentration,  etc.,  with  Notes  on  the  Geol- 
ogy of  the  Flint  Creek  Mining:  District,"  M.  #.,1890.    Rec.    "The  Granite 
Mountain  Mine,"  Engineering  and  Mining  Journal,  Dec.  10,  1887 ;  Nov. 
23,  1889.    E.  G.  Spilsbury,  "  Placer  Mining  in  Montana,"  Ibid.,  Sept.  3, 
1887,  p.  167. 


222  KEMPS   ORE  DEPOSITS. 

miles  north  of  Helena,  in  the  town  of  Marysville,  is  the  Drum- 
lummon  group  of  veins,  which  carry  refractory  silver  and  gold 
ores,  in  a  quartz  gangue,  on  the  contact  between  a  granite  knob 
and  the  surrounding  metamorphic  schists.  There  are  also  other 
veins  in  the  granite.  Dikes  of  intrusive  rocks  occur  associated 
with  the  ore  bodies.1 

2.10.12.  Missoula  County.     In  the  northwestern  corner  of  the 
State  is  a  region  of  very  recent  development,  and  more  especially 
since  the  Northern  Pacific  Railroad  has  been  built  through  it.    At 
Iron  Mountain  and  elsewhere  mining  districts  are  growing  up,  but 
available  descriptions  have  not  yet  been  received.     (See  paper  by 
G.  E.  Culver,  cited  under  2.10.04.)     In  Meagher  County,  in  the 
central  part  of  the  State,  there  are  a  number  of  mining  districts 
in  the  Little  Belt    Mountains.     Neihart  is  the  location  of  some 
rich  silver  mines,  and  is  now  connected  with  Great  Falls  by  rail. 
Other  camps  are  as  yet  too  remote  for  profitable  working. 

IDAHO. 

2.10.13.  Geology. — The  southern   part   of  the   State   extends 
into  the  alkaline  deserts  of  the  Great  Basin  and  is  dry  and  barren. 
North  of  this  is  the  Snake  River  Valley,  which  is  filled  by  a  great 
flood  of  recent  basalt  which  stretches  from  the  Wyoming  line 
nearly  across  the  State.     North  of  the  Snake  River  a  large  area 
of   granite   appears  in    the  western    portion  and  contains    many 
mines.     Extensive   deposits  of  gravel  also  occur.     Metamorphic 
rocks  and  Paleozoic  strata  largely  constitute  the  northern  portion 
of  the  State,  and  are  penetrated  by  many  igneous  intrusions.    The 
eastern  part  lies  on  the  western  slopes  of  the  Bitter  Root  Moun- 
tains, whose   general  geology  was  outlined  under  Montana.     The 
geology  of  Idaho  has  been  but  slightly  studied,  and  the  few  re- 
liable records  have  resulted  from  the  scattered  itineraries  of  Hay- 
den's  survey,  isolated  mining  reports,  and  the  collections  of  the 
Tenth  Census.2 

1  J.  E.  Clayton,  "  The  Drumlummon  Group  of  Veins,"  etc.,  Engineer- 
ing and  Mining  Journal,  Aug.  4  and  11,  1888,  pp.  85,  106.  S.  F.  Emmons, 
Tenth  Census,  Vol.  XIII.,  p.  97. 

3  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  52.  F.  H.  Bradley,  Hay  den's 
Survey,  1872,  p.  208.  F.  V.  Hayden,  Ann.  Rep.,  1871,  pp.  1,  147  ;  1872,  p. 
20.  J.  S.  Newberry,  "Notes  on  the  Geology  and  Botany  along  the  North- 
ern Pacific  Railroad,"  Annals  N.  Y.  Acad.  Sci.,  III.  252.  Raymond's  Re- 
ports on  Mineral  Resoures  West  of  the  Rocky  Mountains.  O.  St.  John, 
Hay  den's  Survey,  1877,  p.  333  ;  1878,  p.  175. 


SILVER  AND   GOLD,   CONTINUED.  223 

2.10.14.  Ouster  County  lies  north  of  Lemhi  and  contains 
several  well-known  mines.  The  Ramshorn  is  in  metamorphic 
slates  on  a  fissure  vein  that  has  rich  chutes  of  high-grade  silver 
ores  in  a  siderite  gangue.  The  Ouster  and  the  Charles  Dickens 
are  farther  west,  near  Bonanza  City,  and  afford  both  silver  and 
gold  in  quartz  gangue  from  veins  in  porphyry.  Smelting  ores  oc- 
cur in  the  region  and  have  been  used  in  some  operations  based  on 
this  treatment.  In  Boise  and  western  Alturas  counties  a  granite 
area  forms  the  greater  part  of  the  surface,  and  in  it  are  numerous; 
productive  veins.  In  the  former  they  are  chiefly  gold  quartz  ex- 
cept in  the  Banner  district,  where  silver  predominates. 

The  placer  deposits  of  Boise  County,  which  were  developed  in 
1863,  were  very  rich,  but  are  now  less  productive  than  in  former 
years.  In  Alturas  County  gold  quartz  veins  occur,  and  also 
others  carrying  silver,  and  the  county  is  a  strong  producer.  The 
Wood  River  mines  in  slates  and  limestones,  southeast  of  the 
granite,  have  already  been  referred  to  under  Example  32a.  Owyhee 
County  is  in  the  southwestern  corner  of  the  State.  It  is  probable 
that  the  granite  of  the  two  last  mentioned  counties  extends  under 
overlying  drift  and  comes  up  again  near  Silver  City  (Becker). 
Southwest  of  it  quartz  porphyry  and  metamorphic  rocks  are  found, 
with  dikes  of  basalt.  Gold  quartz  and  high-grade  silver  ores  are 
present.  The  Poorman  Lode  is  famous  for  ruby  silver  ores.  W. 
P.  Blake  mentions  seeing  a  piece  from  this  mine  at  the  Paris  Ex- 
position which  weighed  about  200  pounds.1  It  was  awarded  a  gold 
medal.  The  crystal  from  which  it  was  broken  weighed  500 
pounds.3  In  Cassia  and  Oneida,  two  other  counties  in  the  southern 
part,  placers  are  being  or  have  been  worked,  and  in  Bear  Lake 
County,  in  the  southeast  corner,  salt  and  sulphur  deposits  are  re- 
corded.3 


1  Amer.  Jour.  Sci.,  ii.,  XLV.  97. 

2  Raymond's  Reports  on  Mineral  Resources  West  of  the  Rocky  Moun- 
tains, 1868,  p.  523. 

3  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  59.     Raymond's  Reiiorts. 
on  Mineral  Resources  West  of  the  Rocky  Mountains,  Rep.  Director  of  the. 
Mint,  1882,  p.  227. 


CHAPTER   XL 

SILVER  AND  GOLD,  CONTINUED.— THE  REGION  OF  THE  GREAT 
BASINr  IN  UTAH,  ARIZONA,  AND  NEVADA. 


UTAH. 

2.11.01.  Geology. — The  eastern  half  of  Utah,  terminating 
with  the  western  front  of  the  Wasatch,  is  in  the  Colorado  Pla- 
teau, but  the  western  is  within  the  limits  of  the  Great  Basin. 
The  plateau  portion  consists  largely  of  Mesozoic  strata,  quite 
horizontal  and  more  or  less  carved  by  erosion.  The  east  and  west 
arch  of  the  Uintah  Mountains,  in  the  northern  part,  has  upheaved 
them,  so  that  where  the  Green  River  has  cut  a  channel  across,  the 
Paleozoic  is  exposed  in  great  strength.  The  Wasatch  range  rises 
with  a  gradual  ascent  from  the  east,  and  then  terminates  with  a 
great  fault  line  having  a  steep  westerly  front.  This  line  of  weak- 
ness-was developed  in  the  Archaean  and  has  been  a  scene  of  move- 
ment even  to  recent  times.  It  is  a  very  important  structural  feat- 
ure. West  of  the  Wasatch,  which  is  a  fine  example  of  block 
tilting  in  mountain-making,  the  .mountains  belong  to  the  Basin 
ranges,  which  are  more  typically  developed  in  Nevada.  The 
Wasatch  section  was  shown  by  the  Fortieth  Parallel  Survey  to  in- 
volve 12,000  to  14,000  feet  of  the  Upper  Archaean  and  nearly 
30,000  feet  of  the  Paleozoic.  In  southern  Utah  the  Triassic  rocks 
are  important  and  contain  some  rich  mines.1 

1  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  38.  C.  E.  Dutton,  Rep.  on 
the  High  Plateaus  of  Utah,  Washington,  1880.  A.  Geikie,  "Archaean 
Rocks  of  the  Wasatch  Mountains,"  Amer.  Jour  Sci.,  iii.,  XIX.  363.  G.  K. 
Gilbert,  •'  Contributions  to  the  History  of  Lake  Bonneville,"  Second  Ann. 
Rep.  Director  U.  S.  Geol.  Survey,  169-200,  and  Monograph II.  "The  An- 
cient Outlet  of  Great  Salt  Lake,"  Amer.  Jour.  Sci.,  iii.,  XV.  256,  XIX.  341; 
see  also  A.  C.  Peale,  Ibid.,  XV.  439.  The  Henry  Mountains,  Washington, 
1877.  Hague,  King-,  and  Emmons,  Fortieth  Parallel  Survey,  Vols.  I.  and 
II.  O.  C.  Marsh,  "On  the  Geology  of  the  Eastern  Uintah  Mountains,"' 
Amir.  Jour.  Sci.,  iii.,  I.  191.  B.  Silliman,  "Geological and  Mineralogical 
No.es  on  Some  of  the  Mining  Districts  of  Utah  Territory,"  Amer.  Jour. 


SILVER  AND   GOLD,   CONTINUED.  225 

2.11.02.  The  greater  number  of   the  Utah  mines  are  for  lead- 
silver  ores  and  have  been  mentioned  under  "  Lead  Silver."     The 
northwestern  county,  Box   Elder,  is  in  the   alkaline  desert  region 
of  the  Great  Basin.     The  mining  districts  occur  in  the  central 
part  of  the  State,  in  the  Wasatch  and  Oquirrh  mountains,  and  are 
also  found  in  the  extreme  southwest. 

2.11.03.  Ontario    Mine.     Nearly   east   of  Salt  Lake   City,   in 
Summit  County,  is  the  Ontario  mine,  a  vein  from  four  to  twenty- 
three  feet  wide  (averaging  eight  feet),  in  quartzite,  but  extremely 
persistent,  being  opened  continuously  for  6000  feet.     In  the  lower 
working  a  porphyry  dike  has  come  in   as  one  of  the  walls.     It  is 
extensively  altered  by  fumarole  action  to  clay.     The  best  parts  of 
the  mine  have  quartzite  walls.     The  ores  consist  of  galena,  gray 
copper,  silver  glance,  blende,  etc.      Other  somewhat   similar   ore 
bodies  are  known  in  the  same  region  but  are  less  developed.1 

2.11.04.  The  lead-silver  veins  of    Bingham   Canon,  in   Salt 
Lake  County,   have    already    been    mentioned.      Reference  may 
again  be  made  to  the  great  bed-veins  of  gold   quartz  associated 
with  them.     Ophir   Canon  and  Dry   Canon,   in  Tooele   County, 
and  the  Tintic  district,  in  Juab  County,  have  also  been  described. 
In   addition  to  the  smelting  ores,  others  have   been   treated  by 
milling.     Quite  recently  interest  has  been  directed  to  the  mines 
of  the   Deep  Creek  district,  on  the   extreme  western  border  of 
Utah,  in  the  Ibapah  range.     Limestones  regarded  by   Blake  as 
Carboniferous,   and  other  sedimentary  rocks,   have  been  broken 
through  by  great  outflows  of  granite,  andesite,  hypersthene-ande- 
site,  etc.     The  ore  bodies  appear  to  be  contact  deposits  in  lime- 
stone near  igneous  rocks,  and  carry  much  free  gold.2 

In  Beaver  County  the  interesting  deposits  of  the   Horn   Silver, 
the    Carbonate,  and   the    Cave  ore  bodies  have  been   mentioned 


Sci.,  iii.,  III.  195.  Wheeler,  Gilbert,  Lockwood  and  others  on  Western 
Utah,  Wheeler's  Survey,  Rep.  Prog.  1869-71-72.  Idem,  Final  Reports, 
Vol.  III. 

1  T.   J.   Almy,  "History  of  the  Ontario  Mine,  Park  City,   Utah," 
M.  E.,  XVI.  35.     "  The  Ontario  Mine,"  Engineering  and  Mining  Journal, 
May  28,  1881,  p.  365.     D.  B.  Huntley,  Tenth  Census,  Vol.  XIII.,  p.  438. 

2  W.  P.  Blake,  "  A<re  of  the  Limestone  Strata  at  Deep  Creek,  Utah, 
and  the  Occurrence  of  Gold,"  etc.,  Amer.  Geol,  January,  1892,  p.  47.    Engi- 
neering and  Mining  Journal,  Feb.  23,  1892,  p.  253.    S.  F.  Emmons,  For- 
tieth Parallel  Survey,  Vol.  II.     J.  F.  Kemp,  "  Petrographical  Notes  on  a 
Suite  of  Rocks  collected  by  E.  E.  Olcott,"  N.  Y.  Acad.  Sci.,  May,  1892. 


226  KEMP'S   ORE  DEPOSITS. 

under  Examples  30</,  33#,  and  32&.  The  great  iron  mines  of  Iron 
County  will  be  found  under  Example  14.  In  Piute  County,  near 
the  town  of  Marysvale,  around  Mount  Baldy,  are  a  number  of 
mines  with  lead-silver  or  milling  ores  in  quartz  porphyry  (copper 
belt),  or  between  limestone  and  quartzite  (Deer  Trail,  Greeneyed 
Monster,  etc.).  Selenide  of  mercury  is  found  in  the  Lucky  Boy.1 

2.11.05.  Example  41.  Silver  Reef,  Utah.  Native  silver,  cerar- 
gerite,  and  argentite,  impregnating  Triassic  sandstones,  and  often 
replacing  organic  remains.  These  deposits  were  earlier  referred 
to  under  Example  21,  p.  80.  They  were  discovered  in  1877.  At 
Silver  Reef  there  are  two  silver-bearing  strata  or  reefs,  with  beds 
of  shale  between.  Above  the  water  line  the  ore  is  horn  silver  ; 
below,  it  is  argentite.  At  times  it  replaces  plant  remains  ;  at  other 
times  no  visible  presence  of  ore  can  be  noted,  although  the  rock 


xxxxx.xx  „„  x^-          ^^ 
x 

•    / 


% 
I 


Runs  into. 
barren  rock 


FIG.  56.  —  Two  sections  of  the  argentiferous  sandstone  at  Silver  Reef, 
Utah.    After  C.  M.  Rolker,  M.  E.,  IX.,  p.  21. 

may  afford  $30  to  the  ton.  The  silver  always  occurs  along  certain 
ore  channels,  distributed  through  parts  of  the  sandstone.  The 
origin  of  the  deposits  has  given  occasion  to  a  vigorous  discussion. 
J.  S.  Newberry  holds  that  the  silver  was  deposited  in  and  with 
the  sandstone  from  the  Triassic  sea,  although  it  may  have  been 
concentrated  since  in  the  ore  channels.  F.  M.  F.  Cazin  holds  that 
the  organic  remains  were  deposited  in  and  with  the  sandstone,  and 
that  these  were  the  immediate  precipitating  agents  of  the  ores. 
R.  P.  Rothwell  explained  them  much  as  does  Rolker,  below.  C.  M. 
Rolker,  who  was  for  some  years  in  charge  of  several  of  the  mines, 
has  also  written  about  them,  and  is  probably  nearest  to  the  truth. 
Rolker  argues  that  the  impregnation  was  subsequent  to  the  forma- 
tion of  the  sandstone,  and  was  caused  by  the  igneous  outbreaks  in 
the  neighborhood,  and  probably  runs  along  old  lines  of  partial 
weakening  or  crushing  that  afterward  healed  up.  Eruptive  rock& 

1  G.  J.  Brush,  "  On  theOnofrite,  etc.,"  Amer.  Jour.  Sci.,  iii.,  XXI.  312. 


SILVER  AND   GOLD,   CONTINUED.  227 

are  known  in  the  neighborhood  of  the  ores  both  in  Utah  and  in  the 
Nacemiento  copper  district  of  New  Mexico.  From  what  we  know 
of  ore  deposits  in  general  this  seems  most  probable.1 


ARIZONA. 


2.11.06.  G-eology. — Arizona  lies  partly  in  the  plateau  region 
and  partly  in  the  Great  Basin.  The  Basin  ranges  converge  with 
the  Rocky  Mountains,  which,  however,  are  chiefly  in  New  Mexico. 
The  uplands  of  the  ranges  are  well  watered  and  covered  with 
timber,  but  the  low-lying  portion  of  the  Great  Basin  is  an  arid 
desert,  and  in  southwestern  Arizona  is  the  hottest  part  of  the  United 
States.  Cretaceous  and  Jura-Trias  largely  form  the  plateau 
region.  Running  southeast  to  northwest  is  the  great  development 
of  Carboniferous  limestone  so  often  referred  to  under  "  Copper," 
and  underlying  this  are  found  Archaean  granites,  gneisses,  etc.  A 
great  series  of  ore  deposits  is  ranged  along  this  contact.  In  the 
southwest  are  mountains  of  granites  and  metamorphic  rocks.  The 
Territory  also  contains  vast  flows  of  igneous  rocks,  and  in  the  pla- 
teau country  between  the  converging  ranges  some  20,000  or  25,000 
square  miles  are  covered  by  them.  The  Grand  Canon  of  the  Colo- 
rado has  laid  bare  a  magnificent  geological  section  of  many  thou- 
sand feet,  from  the  Archaean  to  the  Tertiary.8 


1  F.  M.  F.  Cazin,  "  The  Origin  of  the  Copper  and  Silver  Ores  inTriassic 
Sand  rock,"  Engineering  and  Mining  Journal,  Dec.  11, 1880,  p.  381 ;  April 
.30,  1881,  p  300.     "  The  Silver  Sandstone  Formation  of  Silver  Reef,"  Ibid., 
May  22,  1880,  p.  351  ,  Jan.  10,  17,  24,  1880,  pp.  25,  48,  79  (Roth well).     A.  N. 
Ja  kson,  "  Silver  in  Sedimentary  Sandstone,"  Rep.  Director  of  Mint,  1882, 
p.  384,  reprinted  from  Cal.  Acad.  Sci.    J.  S.  Newberry,  "  Report  on  the 
Properties  of  the  Stormont  Silver  Mining  Company,"  etc.,  Engineering 
and   Mining  Journal,  Oct.  23,  1880,   p.  269.     "The  Silver  Reef  Mines," 
Ibid.,  Jan.  1,  1881,  p.  4.     C.  M.  Rolker,  "  The  Silver  Sandstone  District  of 
Utah,"  M.  E.,  IX.  21. 

2  "Central  Arizona,"  Engineering  and  Mining  Journal,  April  23, 
1881,  p.  285.     "Colorado  River  of  the  West,"  review  of  Ives  Expedition, 
Amer.  Jour.  Sci.,  ii.,  XXXIII.  387.    G.  F.  Becker,  Tenth  Census,  Vol. 
XIII.,  p.  44.    C.  E.  Dutt  jn,  "  Th.e  Physical  Geology  of  the  Grand  Canon 
District,"  abstract  of  Monograph  II.,  Second  Ann.  Rep.  Director  U.  S. 
Geol.  Survey,  49-161  ;  see  also  the  monograph.     Patrick  Hamilton,  The 
Resources  of  Arizona,  A.  L,  Bancroft  &  Co.,  San  Francisco,  1884.    B.  Silli- 
man,  "  Report  on  Mining  Districts  of  Arizona,  near  the  Rio  Colorado,"  En- 
gineering and  Mining  Journal,  Aug.  11,  1877,  p.  Ill  ;  taken  from  Amer. 
Jour.  Sci.,  ii.  XLI.  289.     C.  D.  Walcott,  "Permian  and  Other  Paleozoic 


228  KEMPS   ORE  DEPOSITS. 

2.11.07.  Apache  County  is  in  the  northeastern  corner.     In  the 
southern  part  of  the  county  gold  and  silver  ores,  in  veins  in  lime- 
stone, associate^,  with  copper  ores,  are   reported,  and  some  small 
placers. 

2.11.08.  Yavapai  County.     Gold  and  silver  ores,  in  quartz  veins, 
in  granite  and  metamorphic  rocks.     The  Black  Range  copper  dis- 
trict has  already  been  referred  to  under  Example  20e. 

Mohave  County.  Silver  sulphides,  arsenides,  etc.,  and  alteration 
products  in  veins  in  granite,  at  times  showing  a  gneissoid  structure. 
Only  the  richest  can  now  be  worked. 

Yuma  County.  Quartz  veins,  with  silver  ores  and  lead  miner- 
als in  metamorphosed  rocks  (gneiss,  slate,  etc.),  or  in  granite. 

Maricopa  County  contains  both  Paleozoic  and  Archaean  expos- 
ures. The  ore  deposits  lie  mostly  along  the  contact  of  the  two,  in 
granite  or  highly  metamorphosed  strata.  They  are  usually  quartz 
veins,  with  silver  ores  and  copper,  lead,  and  zinc  minerals.  The 
Globe  district,  extending  also  into  Final  County,  is  the  principal 
one.  Mention  has  already  been  made  of  it  under  "  Copper,"  Ex- 
ample 20c. 

Final  County  adjoins  Maricopa  on  the  south  and  contains  a 
number  of  important  mines.  They  produce  mostly  silver  ores, 
with  lead  and  copper  associates,  and  some  blende.  The  gangue 
minerals  are  quartz,  calcite,  etc.,  occasionally  manganese  com- 
pounds, and  sometimes,  in  the  granites,  barite.  Limestone,  slate, 
sandstone,  and  quartzite,  as  well  as  granite,  diabase,  and  diorite, 
occur  as  wall  rock. 

2.11.09.  Silver    King  Mine.     A  central  mass   or  chimney  of 
quartz,  with  innumerable  radiating  veinlets  of  the  same,  carrying 
rich  silver  ores  and  native  silver,  in  a  great  dike  of  feldspar  por- 
phyry, with  associated  granite,  syenite  (Blake),  porphyry,  gneiss, 
and  slates,  all  of  Archaean  age.     The  veinlets  ramify  through  the 
strongly  altered  porphyry,  and  form  a  stockwork,  which  furnishes 
the  principal  ores.     In  the  region  are  also  Paleozoic  strata,  whose 
upper  limestone  beds  are  referred  by  Blake  to  the  Carboniferous. 
The  minerals  at  the  mine   are  native  silver,  stromeyerite,  argen- 
tite,  sphalerite,  galenite,  tetrahedrite,  bornite,  chalcopyrite,  pyrite, 
quartz,  calcite,  siderite,  and,  as  an  abundant  gangue,  barite. 

Groups  of  the  Kanab  Valley,  Arizona,"  Amer.  Jour.  Sci.,  iii.,  XX.  221. 
"  Pre-Carboniferous  Strata  in  the  Grand  Canon  of  the  Colorado,  Arizona," 
Amer.  Jour.  Sci.,  December,  1883,  437.  Wheeler's  Survey,  Vol.  III.,  and 
Supplement. 


SILVER  AND   GOLD,   CONTINUED.  229 

Graham  County  contains  the  Clifton  copper  district,  referred 
to  under  Example  20«. 

Cochise  County  is  the  southeastern  county,  and  contains  the 
Tombstone  district,  the  most  productive  of  the  precious  metals  in 
the  Territory. 

2.11.10.  Tombstone.     A    great  porphyry  dike  up  to   TO  feet 
wide,  cutting  folded  Paleozoic  strata,  and  itself  extensively  faulted 
and  altered,  and  carrying  above  the  water  line  in  numerous  verti- 
cal joints,  or  partings,  quartz  with  free  gold,  horn  silver,  and  a  lit- 
tle pyrite,  galenite,  and  lead  carbonate.   •  Curiously  enough,  in  the 
porphyry  itself,  and  far  from  the  quartz  veins,  flakes  and  scales  of 
free  gold  have  been  found,  evidently  introduced  in  solution.     Ore 
also  occurs  along  the  side  of  the  dike.     There  are  also  other  fis- 
sures parallel  with  this  principal  dike,    and    still    another   series 
crossing  these  and  the  axis  of  the  great  anticline  of  the  district. 
Connected  with  these   fissure  veins  are  bedded  deposits   in   the 
limestone,  along  the  bedding  planes  or  dropping  from  one  to  an- 
other, appearing  to  have  originated  by  replacement.     Blake  offers 
two  explanations  of  the  first-mentioned  dike   deposit — either  that 
the  dike  itself  held  the  precious  metals,  or  that  they  came  from  the 
pyrite  of  the  adjoining  strata.     Several  other  mining  districts  of 
less  note  occur  in  the  county.     The  important  copper  deposits  of  the 
Bisbee  region  have  already  been  mentioned  under  Example  20/! 

2.11.11.  Pima  County  is  the  central   county  of  the  southern 
tier  and  has  Tucson  as  its  principal  city.     There  are  numbers  of 
mines  of  the  precious  metals,  and  a  few  less  important  copper  de- 
posits. 

Yuma  County,  in  the  southwestern  corner,  has  some  mines 
along  the  Colorado  River,  on  quartz  veins  in  metamorphosed  rocks, 
containing  silver  and  lead  minerals.1 


1  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  44.  G.  H.  Birnie,  "  Castle 
Dome  District,"  Wheeler's  Survey,  1876,  p.  6.  W.  P.  Blake,  "  The  Geology 
of  Tombstone,  Ariz.,"  M.  E.,  X>-334,  Engineering  and  Mining  Jour- 
nal, June  24,  1882,  p.  328 ;  The  Silver  King~Mine,  a  short  monograph, 
New  Haven,  March,  1883.  Rec.  See  also  Engineering  and  Mining  Jour- 
nal, April  28,  1883,  p.  238,  J.  F.  Blandy,  "The  Mining  Region  around 
Presrott,  Ariz.,"  M.  E.,  XI.  286,  Engineering  and  Mining  Journal,  July 
21,  1883.  "  On  Tombstone,  Ariz.,"  Ibid.,  May  7,  1881,  p.  316  ;  March  18, 
1882,  p.  145.  "Silver  in  Arizona,"  General  Review,  Engineering  and  Min- 
ing Journal,  Sept.  21  and 2$,  1880,  pp.  172,  203.  "Central  Arizona,"  Ibid., 
April  23,  1881,  p.  285.  O.  Loew,  "Hualapais  District,"  Wheeler's  Survey, 


330  KEMP'S   ORE  DEPOSITS. 

NEVADA. 

2.11.12.  Geology. — Nevada  lies  almost  entirely  in  the  Great 
Basin,  only  the  western  portion  being  in  the  Sierras.     The  surface 
is  thus  largely  formed  by  the  dried  basins  of  former  great  lakes, 
principally  Lakes  Lahontarr  and  Bonneville.     A    large  number  of 
ranges  extend  north  and  south  through  the  State,  known  collec- 
tively as  the  Basin  ranges.     They  have  been  formed  by  block  tilt- 
ing  on  a  grand  scale  and  present    enormously  disturbed  strata. 
The  geological  sections  exposed  are  of  surpassing  interest  (cf.  Ex- 
ample 36),  and  show  Archaean  and  Paleozoic  in  great  thickness.    In 
these  mountains  are  found  the  mining  districts,   while   between 
them  lie  the  alkaline  plains.1 

2.11.13.  Lincoln  County  is  in  the  southeastern  corner  and  con- 
tains a  number  of  small  mining  districts.     The  ores  are  in  general 
silver-lead  ores  in  limestone,  or  veins  with  sulphuret  ores  in  quartz- 
ite  and  granite.     Pioche  is  one  of  the  principal  towns,  near  which 
is  found  the  once  famous  and  now  reopened  Raymond  &   Ely 
mine.     A  strong  fissure  cuts  Cambrian  quartzite  and  overlying 
limestone,  where  the  latter  has  not  been  eroded,  and  is  occupied 
by   a  great  porphyry  dike.     Along  the  contact  between  the  por- 
phyry and  the  wall  rock  the  chutes  of  ore  have  been  found.     Mr. 
Ernest  Wiltsee,  at  the  Montreal  meeting  of  the  American  Insti- 
tute of  Mining  Engineers,  February,   1893,  described  and  figured 
the  Half  Moon  mine,  on  this  same  great  fissure,  where  the  quartz- 


1876,  p.  55.  B.  Silliman,  "Report  on  the  Mining  District  of  Arizona  near 
the  Rio  Colorado,"  Amer.  Jour.  Sci.,  ii.,  XLI.  289;  see  also  Engineering 
and  Mining  Journal,  Aug.  11,  1877,  p.  111.  Raymond's  Reports,  and 
those  of  the  Director  of  the  Mint. 

1  J.  Blake,  "The  Great  Basin,"  Proc.  Cal.  Acad.  Sci.,  IV.  275,  Amer. 
Jour.  Sci.j  iii.,  VI.  59.  W.  P.  Blake,  "On  the  Geology  and  Mines  of  Ne- 
vada" (Washoe  silver  region),  Quar.  Jour.  Geol.  Sci.,  Vol.  XX.,  p.  317. 
H.  G.  Clark,  "Aurora,  Nev.:  a  Little  of  its  History,  Past  and  Present," 
School  of  Mines  Quarterly,  III.  133.  G.  K.  Gilbert,  "A  Theory  of  the 
Earthquakes  of  the  Great  Basin,  with  a  Practical  Application,"  Amer. 
Jour.  Sci.,  iii.,  XXVII.  49.  I.  C.  Russell,  "Geology  end  History  of  Lake 
Lahontan,  a  Quaternary  Lake  of  Northwestern  Nevada."  Monograph  XL, 
U.  S  Geol.  Survey ;  also  Third  Ann.  Rep.  Director  U.  S.  Geol.  Survey, 
195.  C.  D.  Walcott,  "  Paleontology  of  the  Eureka  District,"  Mononraph 
VIII.,  U.  S.  Geol.  Survey.  Gilbert,  Wheeler,  Lockwood,  and  others, 
" Eastern  Nevada:  Notes  on  its  Economic  Geology,"  WJieeler's  Survey, 
Rep.  Prog.,  1869,  71,  72  ;  also  Vol.  III.  and  Supplement.  For  further  lit- 
erature, see  under  Example  36. 


SILVER  AND   GOLD,   CONTINUED.  231 

Ite  still  retained  a  limestone  cap.  The  ore-bearing  solutions,  on 
reaching  a  shaly  streak  containing  a  limestone  layer,  departed 
from  the  fissure  and  followed  under  the  limestone,  so  as  to  form  a 
lateral  enlargement,  much  like  those  described  and  figured  from 
Newman  Hill,  Colorado,  under  2.09.10.  The  Pahranagat  and  Tern 
Pahute  districts,  still  farther  south,  have  had  some  prominence, 
but  the  whole  region  is  so  far  from  the  lines  of  transportation  that 
the  conditions  are  hard  ones.1 

2.11.14.  Ney   County,  next   west,  has   an  important  mining 
center,    in   its  northern   portion,    around    the    town    of   Belmont. 
Quartzite   and  slates  rest  on  granites  in   the  order  named,  and  in 
them  are  veins  with  quartz  gangue  and  silver  chlorides,  affording 
very  rich  ores.     Southeast  of  Belmont  is  Tybo.2 

2.11.15.  White  Pine  County  lies  to  the  northeast,  and  contains 
the  White  Pine  district.      The  principal  town  is  Hamilton,  about 
110  miles  south  of  Elko,  on  the  Central  Pacific.       The  Humboldt 
range  is  prolonged   southward  in   some   broken    hills,    consisting 
chiefly    of  folded   Devonian  limestone.     At  Hamilton   these    are 
bent  into  a  prominent  anticline,  and  this  has  a  strong  fissure  cross- 
ing the  axis.     The  geological  section  is  Devonian  limestone,  thin 
calcareous  shale,  thin  siliceous  limestone,  argillaceous  shale,  prob- 
ably Carboniferous  sandstone,  and  Carboniferous  limestone.     The 
ore  bodies  occur,  according  to  Arnold  Hague,  in  four  forms,  all  in 
the  Devonian  limestone:  (l)  in  fissures  crossing  the  anticlinal  axis; 
(2)  in  contact  deposits  between  the  limestones  and  shales;  (3)  in  beds 
or  chambers  in  the  limestone  parallel  to  the  stratification;  (4)  in  ir- 
regular vertical  and  oblique  seams  across  the  bedding.     The  ore  is 
chiefly  chloride  of  silver  in  quartz  gangue.     It  is  thought  by  Mr. 
Hague  to  have  probably  come  up  through  the  main  cross  fissure, 
and,  meeting  the  impervious  shale,  to  have  spread  through    the 
limestone  in  this  way.3 

Egan  Cafion  is  in  the  northern  part  of  the  county  and  shows  a 
geological  section  of  granite,  quartzite,  and  slate  in  the  order 
named.  In  slates,  and  perhaps  extending  into  the  quartzite,  is  a 
quartz  vein  five  to  eight  feet  wide  carrying  gold  and  silver  ores. 

1  E.  P.  Howell,  Wheelers  Survey,  III.  257.     G.  M.  Wheeler,  Report, 
Wheelers  Survey,  1869,  p.  14. 

2  S.  F.  Emmons,  Survey  of  the  Fortieth  Parallel,  Vol.  III.,  p.  393.    G. 
K.  Gilbert,  "On  Belmont  and  Neighborhood,"  Wheeler's  Survey,  III.  36. 

8  J.  E.  Clayton,  "Section  of  the  Rocks  at  Hamilton,  Nev.,"  Col. 
Acad.  Sci.  A.  Hague,  Fortieth  Parallel  Survey,  Vol.  III.,  p.  409. 


232  KEMP'S  ORE  DEPOSITS. 

Eureka  County  is  the  next  county  west  of  White  Pine.  The 
deposits  at  Eureka  have  already  been  described  under  "  Lead-sil- 
ver "  (Example  36). 

2.11.16.  Lander  County  lies  next  west  of  Eureka.     The  Toy- 
abe  range  runs  through  it  from  north  to  south  and  in  its   southern 
portion,  in  Ney  County,  contains  the  Belmont  deposits.     (See  above, 
2.11.14.)     At  Austin,  which  is  80  or  90  miles  south  of  the  Central 
Pacific  Railroad,  now  connected  with  it  by  a  branch,  are  the  mines 
of  the  Reese  River  district,  named  from  the  principal  stream  near 
by.     From  Mount  Prometheus,  which  consists  of  biotite  granite 
or  granitite,  and  which  is  pierced  by  a  great  dike  of  rhyolite,  a 
western   granite   spur  runs  out  known   as  Lander  Hill.     The  ore 
bodies  are  in  this  hill,  and  are  narrow  fissure  veins  with  a  general 
northwest  and  southeast  trend,  carrying  rich  ruby  silver  ores,  with 
gray  copper,  galena,  and  blende,  in  a  quartz  gangue  with  associated 
rhodochrosite  and  calcite.     They  are  also  often  faulted.     At  times 
they  show  excellent   banded   structure.     Antimony  has  recently 
been  found  in  this  region.1     (See  under  "  Antimony.") 

2.11.17.  Elko   County  lies  north  of  White  Pine  and  Eureka 
counties  and  contains  the  Tuscarora  mining  district.     The  depos- 
its are  high-grade  silver  ores  in  veins,  in  a  decomposed  hornblende 
andesite.2 

Humbol4^County  is  the  middle  county  of  the  northern  tier, 
and  _£OJ3-fcaiira~sr number  of  mining  districts,  which  produce  botli  sil- 
ver and  gold  from  quartz  veins  in  the  Mesozoic  slate.  Small 
amounts  of  the  precious  metals  come  also  from  Washoe  County,  in 
the  northwest  corner  of  the  State.3 

Churchill  County  adjoins  Lander  on  the  west  and  possesses  a 
few  silver  mines. 

Esmeralda  County,  in  the  southwest,  has  a  considerable  num- 
ber of  rich  silver  and  gold  mines,  which  produce  high-grade  ores 
from  veins,  with  a  quartz  gangue  in  metamorphic  rocks,  slates, 
schists,  etc.  (See  also  under  "  Nickel.") 

2.11.18.  Storey  and  Lyon  are  two  small  counties  in  the   west- 
ern central  portion  of  the  State,  but  the  former  contains  the  most 
important  and  interesting  ore  deposit  in  Nevada,  if  indeed  it  is  not 
the  largest  and  richest  single  vein  yet  discovered. 


1  S.  F.  Emmons,  Fortieth  Parallel  Survey,  Vol.  III.,  p.  349. 

2  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  84. 

3  Ibid.,  p.  33. 


SILVER  AND    GOLD,    CONTINUED. 


233 


2.11.19.  Comstock  Lode.  A  great  fissure  vein,  four  miles 
long,  forked  into  two  branches  above,  along  a  line  of  faulting  in 
eruptive  rocks  of  the  Tertiary  age  and  chiefly  andesites.  In  the 
central  part  of  the  vein  the  displacement  has  been  about  3000 
feet,  shading  out,  however,  at  the  ends.  The  ores  are  high-grade 
silver  ores  in  quartz,  and  occur  in  great  bodies,  called  "  bonanzas," 
along  the  east  vein.  Over  $325,000,000  in  gold  and  silver  has 
been  extracted,  in  the  ratio  of  two  of  the  former  to  three  of  the 


TiahX  of 
M*  Davidso 


FIG.  57.—  Section  of  Comstock  Lode  on  line  of  Sutro  Tunnel.    After  G.  F. 

Becker,  Monograph  TIL,  U.  S.  Geol.  Survey.     The  colors  of  the 

original  are  h-'re  indicated  by  line-work. 

latter.  The  vein  lies  on  the  easterly  slope  of  a  northeasterly  spur 
of  the  Sierras.  West  of  it  is  Mount  Davidson.  The  outcroppings 
lie  on  the  flank  of  the  latter,  about  6500  feet  above  the  sea  and 
1500  feet  below,  the  summit.  The  general  strike  of  the  vein  is 
east  of  south  and  it  dips  east.  Views  regarding  the  geology  of 
the  Comstock  have  changed  in  the  course  of  years,  as  they  have 
been  influenced  by  the  successive  writings  of  Von  Richthofen, 
King,  Church,  Becker,  and  Hague  and  Iddings,  the  points  in  es- 
pecial controversy  being  the  determinations  of  the  rock  species. 
2.11.20.  It  may  be  remarked  that  the  whole  scheme  of  the 


234  KEMP'S   ORE  DEPOSITS. 

classification  of  our  volcanic  (effusive)  rocks  rests  largely  on  Von 
Richthofen's  early  studies,  and  that  perhaps  the  most  important 
generalization  of  late  years  is  due  to  the  work  of  Hague  and  Id- 
dings  on  the  same.  Von  Richthofen  (1885)  described  the  ore  body 
as  filling  a  fissure  on  the  contact  of  a  so-called  syenite  and  an 
eruptive  rock  that  he  called  "propylite."  The  ore  and  gangue 
are  thought  to  have  been  brought  up  from  below  by.solfataric  ac- 
tion, in  which  fluorine,  chlorine,  and  sulphur  were  the  principal 
dissolving  agents.  Clarence  King  (1867-68,  published  in  1870) 
brings  out  forcibly  the  fact  that  the  footwall  of  the  vein  approxi- 
mates closely  the  natural  continuation  of  Mount  Davidson,  and 
contends  that  the  vein  filled  a  fissure  between  the  syenite  of  which 
Mount  Davidson  consists  and  the  late  Tertiary  eruptive  rocks 
poured  out  against  its  flanks.  He  traced  the  geological  succession 
of  these  and  explained  the  filling  of  the  vein  by  solfataric  action, 
attendant  on  a  thin  dike  of  andesite,  which  forced  its  way  into  the 
contact.  J.  A.  Church  (1877)  thought  that  the  diorite  (called  sy- 
enite above)  of  Mount  Davidson  had  been  poured  out  originally  in 
thin  horizontal  sheets,  w^hich  were  folded  in  east  and  west  folds. 
This  was  to  account  for  the  bedding  of  the  rocks  of  the  lode  as 
now  seen.  On  the  diorite  was  poured  out  next  the  propylite, 
likewise  in  successive  horizontal  sheets.  Then  they  were  all 
tilted  along  north  and  south  axes,  and  eruptions  of  andesite  pene- 
trated between  their  sheets  in  very  large  amount.  Further  move- 
ments forced  the  convexities  of  the  first-formed  folds  against  the 
andesites  and  crowded  their  substance  sidewise,  to  some  extent, 
into  the  synclinals.  This  movement  slightly  parted  the  beds,  af- 
fording watercourses  through  which  rose  siliceous  waters.  These 
dissolved  away  the  neighboring  beds,  leaving  extensive  quartz 
bodies  in  their  places.  They  also  removed  the  andesite  caps.  No 
ore  was  formed  as  yet.  Now  followed  great  trachyte  eruptions 
on  the  east,  and  they  loaded  the  hanging  wall  of  the  lode  so 
heavily  as  to  cause  a  downward  movement  of  it  on  the  foot, 
making  a  new  series  of  openings,  and  into  these  poured  the  ore- 
bearing  solutions  which  brought  the  precious  metals.  No  one 
who  has  intelligently  followed  this  explanation  will  doubt  that 
Mr.  Church  has  shown  great  ingenuity,  and  yet  few  would  be  in- 
clined to  have  very  much  confidence  in  this  long,  unnatural  hy- 
pothesis when  a  simple  course  will  lead  to  the  same  results.  At 
the  time  of  Mr.  Church's  visit  the  workings  were  becoming  very 
deep  and  the  great  heat  which  has  been  since  such  an  obstacle  was 


SILVER  AND    GOLD,   CONTINUED.  235 

manifesting  itself.  Flooded  drifts,  it  was  thought,  had  been 
observed  to  grow  hotter,  and  from  this  the  hypothesis  of  kaolin- 
ization  was  conceived.  It  was  that  the  kaolinization  of  the  feld- 
spar in  the  deeply  buried  rock  occasioned  the  heat  of  the  lode. 

2.11.21.  G.  F.  Becker  (1879-82)  comments  on  the  excessive 
alteration  which  the  rocks  have  undergone,  as  it  figures  largely  in 
his  hypothesis  of  origin.     He  then  traces  the  results    of   faulting, 
and   shows  that  under  conditions  like  those  present   the  surface 
would  tend  to  assume  a  logarithmic  curve,  which  coincides  sur- 
prisingly well   with  the  present  outline  of  the   country.      After 
describing  the  lode  itself,  the  origin  of  its  metalliferous  contents 
is  traced  as  follows.     Waters  under  hydrostatic  pressure  from  the 
heights  to  the  west  are   supposed  to  have  percolated  toward  the 
lode,  passing  through  deeply  buried  regions  of  heat.     They  were 
probably  diverted  from  rising  directly  through  the   lode  by  an 
impervious  clay  seam,  and  were  thus  forced  to  soak  through  the 
diabase  hanging,  relieving  it  in  passage  of  the  metals,  which  were 
afterward    deposited    in    the   higher  portions  of   the  lode.     The 
metals  themselves  were  probably  largely  derived  from  the  augite 
of  the  rock.     Mr.  Becker  had  as  an  associate  Dr.  Carl  Barus,  who 
studied  the  heat  phenomena  (especially  the  hypothesis  of  kaolini- 
zation) and  the  electrical  manifestations  of  the  lode.     The  result 
of  Dr.  Barus's  careful  experiments  threw  great  doubt  on  kaolini- 
zation as  a  source  of  heat.     The  electrical  experiments  were  not 
satisfactory.     They  were  carried  on  also  at  Eureka,  Nev.,  but  no 
very  definite  results  were  reached. 

2.11.22.  The    correct    determination    of   the    eruptive   rocks 
neighboring  to  the  Comstock  has  been  of  great  importance,  not 
alone  because  of  their  scientific  interest,  but  as  bearing  on  the  fact 
as  to  whether  the  lode  itself  was  a  contact  fissure  between  two 
di ffe rent  rocks,  or   whether  it    was  simply  a   fissure  vein.     It  is 
worthy  of  note  that  in  connection  with  it   Yon  Richthofen  de- 
veloped one  of  the  first  important  attempts  to  classify  the  vol- 
canic rocks,  and  that  Hague  and  Iddings  have  finally  urged  that 
the   peculiar  crystalline    structures  of   all  eruptive  rocks  depend 
primarily  on  the  heat  and  pressure  (i.e.,  depth  below  the  surface) 
under  which  they  have  solidified,  destroying  thus  the  time  ele- 
ment in  classification.     This  is,  to  be  sure,  an  old  idea,  but  it  gains 
its  best  confirmation  from  the  Comstock.     Von  Richthofen,  in  his 
report  to  the  Sutro  Tunnel  Company,  and  in  his  later  memoir  on 
"  The  Natural  System  of  the  Volcanic  Rocks "  (  Gal.  Acad.  Sci., 


236  KEMP'S   ORE  DEPOSITS. 

1867;  also  Zeitschrift  d.  d.  yeol.  GeselL,  1868,  663),  distinguished 
in  the  Washoe  district  syenite,  metamorphic  rocks,  quartz-por- 
phyry, propylite,  sanidine-trachyte,  and  very  subordinate  andesite. 
Mr.  King  referred  much  of  the  propylite  of  Yon  Richthofen  to 
andesite,  but  retained  the  propylite  as  a  distinct  species,  although 
remarking  the  close  affinities  of  the  two.  The  quartz-porphyry  he 
called  quartz-propylite.  In  other  respects  no  changes  are  intro- 
duced. Zirkel  (Fortieth  Parallel  Survey,  Vol.  VI.)  determined 
the  syenite  as  granular  diorite,  and  while  accepting  hornblende- 
propylite  and  quartz-propylite  as  separate  species,  the  greater  part 
of  the  quartzose  rock  he  called  dacite.  He  introduced  for  the 
first  time  augite-andesite,  rhyolite,  and  basalt.  Mr.  Church  paid 
less  attention  to  lithology,  and  used  the  terms  of  his  predecessors 
somewhat  loosely.  Mr.  Becker  makes  the  following  classifica- 
tion :  granular  diorite,  porphyritic  diorite,  micaceous  diorite- 
porphyry,  quartz-porphyry,  earlier  diabase,  later  diabase,  earlier 
hornblende-andesite,  augite-andesite,  later  hornblende-andesite, 
and  basalt.  In  this  it  will  be  seen  that  several  new  varieties  are 
introduced,  but  the  main  mass  of  Mount  Davidson  was  still  con- 
sidered diorite,  and  the  vein  was  thought  to  lie  between  this  and 
some  of  the  other  species  mentioned,  especially  diabase.  In  1885, 
Arnold  Hague  and  J.  P.  Iddings  completed  new  microscopical 
studies  upon  the  materials  collected  by  Mr.  Becker,  and  the  re- 
sults were  published  as  Bulletin  17  of  the  United  States  Geologi- 
cal Survey  ("On  the  Development  of  Crystallization  in  the 
Igneous  Rocks  of  Washoe,"  etc.).  These  two  writers  had  had 
more  to  do  with  the  eruptive  rocks  of  the  Great  Basin  and  the 
Pacific  slope  than  any  other  geologists,  and  hence  brought  to  the 
review  an  exceptional  experience.  Nowhere  else  in  the  world  are 
such  exposures  and  thorough  sections  afforded,  alike  in  depth  and 
in  horizontal  extent.  They  proved  that  the  diabase  and  augite- 
andesite  shade  into  each  other,  the  differences  in  crystallization 
being  due  to  depth  ;  that  the  hornblende  of  the  so-called  diorite 
was  largely  secondary  from  original  augite,  being  derived  by 
paramorphic  change  (uralitization),  and  that  the  diorite  was  a 
structural  variety  of  the  diabase ;  that  the  porphyritic  diorites 
shade  into  the  earlier  hornblende-andesites  and  are  structural 
varieties  of  them  ;  that  the  mica-diorites  and  hornblende-andesite 
are  identical  in  the  same  way  ;  that  the  assumed  Pre-Tertiary  age 
of  the  quartz -porphyry  was  unwarranted,  and  that  it  was  partly 
dacite  and  partly  rhyolite,  the  two  shading  into  each  other  ;  that  the 


SILVER  AND   GOLD,    CONTINUED.  237 

younger  diabase,  so  called,  of  the  sub-surface  dike  was  identical  with 
the  rock  elsewhere  occurring  on  the  surface  and  called  basalt,  and 
was  really  a  basalt,  owing  its  holocrystalline  character  to  its  depth  ; 
and  finally, — the  most  important  conclusion  of  all  in  this  connec- 
tion, although  the  other  conclusions  are  among  the  most  important 
advances  made  in  late  years, — "  that  the  Comstock  Lode  occupies 
a  line  of  faulting  in  rock  of  Tertiary  age,  and  cannot  be  con- 
sidered as  a  contact  vein  between  two  different  rock  masses." 
The  crystalline  structure  of  the  Washoe  rocks  has  been  subse- 
quently treated  by  Mr.  Becker.  ("  The  Washoe  Rocks,"  Bull. 
Cal.  Acad.  Sci.,  Vol.  II.,  p.  93,  January,  1887  ;  "Texture  of  Mas- 
sive Rocks,"  Amer.  Jour.  Sci.,  ii.,  Vol.  XXXIIL,  p.  50,  1887.) 
The  various  structures — granular,  porphyritic,  and  glassy — are  re- 
ferred more  to  differences  in  composition  and  fluidity  than  to  cir- 
cumstances of  solidification.1 


1  G.  F.  Becker,  "  Geology  of  the  Comstock  Lode  and  the  Washoe  Dis- 
trict," Monograph  III.,  U.  S.  Geol.  Survey.  Rec.  See  also  Engineering 
and  Mining  Journal,  March  1,  1884,  p.  162 ;  Second  Ann.  Rep.  Director 
U.  S.  Geol.  Survey.  Rec.  J.  A.  Church,  The  Comstock  Lode :  Its  Forma- 
tion and  History.  New  York,  John  Wiley  &  Sons.  Reviewed  in  Engi- 
neering and  Mining  Journal,  Feb.  21, 1880,  p.  397.  See  also  shorter  papers 
in  the  Engineering  and  Mining  Journal,  Dec.  28,  1878,  p.  456 ;  July  19, 
1879,  p.  35 ;  Dec.  12,  1885,  p.  397 ;  Jan.  23,  1886,  p.  52.  "  On  the  Changes 
in  the  Comstock  Vein,"  Engineering  and  Mining  Journal,  Dec.  18,  1886, 
p.  434  ;  "  The  Discovery  of  the  Comstock  Lode,"  Ibid.,  Dec.  5  and  19, 1891, 
and  other  papers  in  1892  by  Dan  Dequille.  Hague  and  Iddings,  "  On  the 
Development  of  Crystallization  in  the  Igneous  Rocks  of  Washoe,  Nev.," 
etc..  Bull  17,  U.  S.  Geol.  Survey.  See  also  Bull.  6,  Cal.  Acad.  Sci.,  and 
Engineering  and  Mining  Journal,  Dec.  11,  1886,  p.  415. 


v* 


CHAPTER   XII. 

THE  PACIFIC  SLOPE  :  WASHINGTON,  OREGON,  AND  CALIFORNIA 


WASHINGTON. 

2.12.01.  Geology.  —Little  is  available  in  the  way  of  systematic 
descriptions  of  the  geology  of  Washington,  and  an  attractive  field 
remains  to  be  developed.  The  rocks  of  the  Rocky  Mountains 
extend  across  the  panhandle  of  Idaho  and  show  in  northeastern 
Washington,  affording  considerable  amounts  of  ores.  They  are 
prevailingly  granite  and  gneiss,  which  have  escaped  being  covered 
by  the  enormous  volcanic  outbreaks  of  Tertiary  and  later  time. 
West  of  the  granites  a  great  plateau  country  of  somewhat  diversi- 
fied surface  is  met.  It  seems  to  have  been  an  ancient  lake  basin, 
but  is  now  covered  by  igneous  rocks  and  deposits  of  volcanic  tuff. 
Still  farther  west  the  Cascade  chain  forms  the  central  divide  of 
the  State.  The  rocks  are  granites,  flanked  by  Paleozoic,  Mesozoic, 
and  metamorphic  strata,  much  like  the  Sierras  of  California. 
They  were  upheaved  in  large  part  before  the  Cretaceous,  and  since 
then  other  movements  have  occurred.  There  are  vast  develop- 
ments of  igneous  rocks,  forming,  as  at  Mount  3=$§Qgi&  (Rainier), 
some  of  the  highest  American  peaks.  West  of  the  Cascade  range 
is  a  great  valley  formerly  marking  a  drainage  system,  but  now 
covered  partly  by  glacial  drift  and  partly  by  the  waters  of  Puget 
Sound.  The  glacial  deposits  are  enormous,  and  render  the  prob- 
lem of  working  out  the  geology  very  difficult.  Some  glaciers  re- 
main on  the  heights  even  to  the  present  day.  West  of  the  Puget 
Sound  Basin  is  the  northerly  extension  of  the  Coast  range,  locally 
called  the  Olympics,  and  largely  Cretaceous  and  Tertiary  strata'.1 


1  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  27.  G.  A.  Bethune,  First 
Ann.  Rep.  State  Geologist,  1891.  A.  Bowman,  "  Mining  Developments  on 
the  Northwest  Pacific  Coast  and  their  Wider  Bearing,"  M.  E.,  XV.  707. 
J.  MacFarlane,  Geol.  Railway  Guide,  second  edition,  p.  262  ;  notes  by 
Pumpelly,  Willis,  and  others.  Rec.  J.  S.  Newberry,  "  Geology  and  Bot- 


THE  PACIFIC  SLOPE.  239 

2.12.02.  Good  descriptions  of  the  ore  deposits  of  Washington 
are  greatly  needed.     The  First  Annual  Report  of  the  State  Geolo- 
gist has  little  of  scientific  value,  and  the  other  accounts  are  ancient 
history.     There  are  gold  placers  in  Yakima,  Stevens,  and  Kittitas 
counties,  largely  worked  by  Chinese.     But  in  Okanogaii  and  Ste- 
vens counties,  in  the  northeast,  the  developments  of  deep  mining 
for  silver  ores,  although  recent,  are   considerable.     The  veins  are 
largely  in  metamorphic  rocks  and  contain  the  usual  sulphides  in 
quartz  gangue.1 

OREGON. 

2.12.03.  Geology. — Northeastern  and  northern  central  Oregon 
are  formed  by  a  prolongation  southward  of  the  igneous  plateaus 
of  Washington.     Slates  and  granite  appear  in  Baker  County  on 
the  east,  in  the  Blue  Mountains,  and  the  geology  seems  to  resem- 
ble the   Sierras.     All  southeastern   Oregon  belongs  in  the  Great 
Basin,  which  comes  north  from  Nevada,  but  is  better  watered 
than  the  southern  portion.     It  is  traversed  by  several  subordinate 
ranges  of  the  block-tilted  basin  type.     Of  these  the  Stein  Moun- 
tains are  the  most  prominent.     The  general  surface  is  formed  by 
Quaternary  lake   deposits  and  great  outbreaks  of  igneous  rocks. 
West  of  the  basin  and  the  plateau  the  Cascade  range  traverses  the 
State,  and  is  cut  by  the  Columbia  River  on  the  north  and  the  Kla- 
math  on  the   south.      The  range  consists  of  granite  and  metamor- 
phic rocks,  etc.,  the  latter  chiefly  Mesozoic.     In  northern  Oregon 
a  broad  valley  intervenes  between  the  Cascade  and  the    Coast 
ranges,  but  in  the  southern  part  the  two  ranges  run  together,  and 
their  distinction  has  been  only  partly  worked  out.     (See  Bull.  33, 

U.  S.  Geol.  Survey.)  In  the  Coast  range  Cretaceous  and  Tertiary 
strata  predominate.2 

any  of  the  Northern  Pacific  Railroad,"  Trans.  N.  Y.  Acad.  Sci.,  III.,  1884, 
p.  253.  C.  A.  White,  "Puget  Group  of  Washington,"  Amer.  Jour.  Sci.y. 
Hi.,  XXXVI.  443.  B.  Willis,  "  Our  Grandest  Mountain  and  Deepest  For- 
est," School  of  Mines  Quarterly,  VIII.  152.  "Report  on  the  Coal  Fields 
of  Washington  Territory,"  Tenth  Census,  Vol.  XV.,  p.  759.  "  Changes  of 
River  Courses  in  Washington  Territory  due  to  Glaciation,"  Bull.  40,  U.  S~ 
Geol.  Survey. 

1  G.  A.  Bethune,  First  Ann.  Rep.  State  Geol  ,  1891.  C.  B.  Fennery 
"  The  Monte  Cristo  District,  Snohomish  County,"  School  of  Mines  Quar- 
terly, November,  1892.  "  The  Mines  of  Kittitas  County,"  Engineering 
and  Mining  Journal,  Dec.  24,  1892,  p.  608. 

3  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  27.    T.  Condon,.  "  On 


240  KEMPS   ORE  DEPOSITS. 

2.12.04.  Oregon  is  an  important  producer  of  gold  both  from 
placers  and  from  veins.     Baker  County,  on  the  east,  presents  the 
characteristic  placers  and  gold  quartz  of  the  California  Sierras,  and 
is  the  most  productive  section  of  the  State.     Grant  and  Josephine 
counties  also  have  placers,  and  smaller  amounts  come  from  a  few 
others.     In  the  extreme  southeast,   near    the    California   line,  is 
Curry  County,  containing  : 

2.12.05.  Example  44a.    Port  Orford.    Auriferous  beach  sands 
at  the  foot  of  gravel  cliffs,  and  shifting  with  the  winds  and  tides. 
At  Port  Orford  the  ocean  has  access  to  great  sea  cliffs  of  gravel 
which  it  breaks  down  by  the  force  of  the  waves.     A  sorting  ac- 
tion ensues,  performed  by  the  undertow  and  the  littoral  current. 
The  heavier  gold  dust  is   concentrated  and  gathered  up  by  the 
miners    at   low    tide.     Some    submarine    work  has   also  been   at- 
tempted.    The  product  is  not  great,  and  the  deposit  is  chiefly  in- 
teresting in  its  scientific  bearing.    It  runs  along  into  California  as 
well.     Auriferous  sands  occur  at  Yakutat  Bay,  Alaska.     (See  J. 
Stanley-Browne,  Nat.  Geog.  Mag.,  Vol.  III.,  1891.)     The  gold  of 
the  Potsdam  sandstones  of  the  Black  Hills  has  been  concentrated  in 
a  similar  way  in  early  geologic  time,  and  the  magnetite  sands  which 
were  referred  to  under  2.03.13  furnish  something  of  a  parallel.1 

Some  Points  Connected  with  the  Igneous  Eruptions  along  the  Cascade 
Mountains  of  Oregon,"  Amer.  Jour.  Sci.,  iii.  XVIII.  406.  J.  S.  Diller, 
"  Notes  on  the  Geology  of  Northern  California,"  Bull.  33,  U.  S.  Geol.  Sur- 
vey. J.  C.  Fremont,  "  Observations  on  the  Rocky  Mountains  and  Oregon," 
Amer.  Jour.  Sci. ,  ii. ,  HI.  192.  George  Gibbs,  ' '  Notes  on  the  Geology  of  the 
Country  East  of  the  Cascade  Mountains,  Oregon,"  Amer.  Jour.  Sci.t  ii., 
XX.  275.  J.  Leconte,  "  On  the  Great  Lava  Flood  of  the  West,  and  on  the 
Structure  and  Age  of  the  Cascade  Mountains,"  Amer.  Jour.  Sci.,  iii., 
VIII.  167,  259.  C.  King,  Fortieth  Parallel  Survey,  Vol.  I.  J.  MacFarlane, 
Geol.  Railway  Guide,  p.  316.  J.  S.  Newberry,  Pacific  R.  R.  Reports,  Vol. 
VI.,  pp.  1-73.  I.  C.  Russell,  "  A  Geological  Reconnoissance  in  Southern 
Oregon,"  Fourth  Ann.  Rep.  Director  U.  S.  Geol.  Survey,  pp.  435-4G2. 

1  G.  F.  Becker,  Tenth  Census,  Vol.  XIII.,  p.  27,  general  account  of 
Oregon.  W.  P.  Blake,  "Gold  and  Platinum  from  Cape  Blanco  (Port  Or- 
ford)," Amer.  Jour.  Sci.,  ii.,  XVIII.  156.  "  Remarks  on  the  Extent  of  the 
Gold  Regions  of  California  and  Oregon,"  etc.,  Amer.  Jour.  Sci.,  ii.,  XX. 
72.  A.  W.  Chase,  "  The  Auriferous  Gravel  Deposits  of  Gold  Bluffs,  Cali- 
fornia," Cal.  Acad.  Sci.,  1874 ;  Amer.  Jour.  Sci.,  iii  ,  VII.  367.  "  Dredging 
for  Gold,"  Engineering  and  Mining  Journal,  June  23,  1883,  p.  360.  B. 
Silliman,  "  Cherokee  Gold  Washings,"  Amer.  Jour.  Sci.,  iii.,  VI.  182.  W. 
P.  Watts,  "  Sands  in  Santa  Cruz  County,  California,"  Rep.  Cal.  State  Min- 
eralogist, 1890,  p.  622. 


THE  PACIFIC  SLOPE.  241 

CALIFORNIA. 

2.12.06.  Geology. — The  topography  and  geology  of  northern 
California  have  been  but  recently  made  clear.  Diller  considers 
that  the  southern  end  of  the  Cascade  range  is  Mount  Shasta ; 
that  the  Sierras  proper  terminate  near  the  north  fork  of  the 
Feather  River,  but  the  line  is  continued  about  fifty  miles  farther 
north,  in  the  Lassens  Peak  volcanic  ridge,  and  that  all  else  west 
and  south  of  Mount  Shasta  belong  to  the  Coast  range.  Central 
California,  as  is  well  known,  has  the  Sierras  on  the  east,  the  great 
Sacramento  Valley  in  the  middle,  with  the  Coast  range  on  the 
west.  The  arid  regions  of  the  Great  Basin  just  touch  the  north- 
eastern corner,  but  on  the  southern  extremity  they  swing  around 
and  form  a  large  part  of  the  State.  The  Great  Basin  portion  is 
formed  by  Quaternary  lake  deposits.  The  Sierras  consist  of  cen- 
tral granite  and  gneiss,  with  great  developments  of  slates  and 
eruptives  on  their  flanks.  The  excessive  metamorphism  has  large- 
ly destroyed  the  fossils,  but  enough  have  been  found  to  prove  that 
while  in  large  part  Jurassic,  yet  Carboniferous  and  Cretaceous 
representatives  are  also  present.  The  western  slopes  have  the 
mantles  of  gravel,  which  have  furnished  so  much  gold,  and  with 
these  are  large  outflows  of  basalt.  The  upheaval  of  the  Sierras 
occurred  before  the  middle  Cretaceous  time.  The  Coast  range  con- 
sists of  rocks  of  late  Cretaceous  and  early  Tertiary  age,  extending 
into  the  Miocene.  They  were  upheaved  in  post-Miocene  time. 
Great  outbreaks  of  andesite  also  occurred,  and  later  basalts.  The 
principal  product  of  California  is  gold,  but  recently  a  district 
which  furnishes  considerable  silver  has  been  developed.  This 
will  first  be  described,  in  order  to  lead  up  to  gold.  The  copper 
and  iron  resources  have  already  been  mentioned,  and  the  mercury, 
antimony,  and  chromium  deposits  remain  for  description  after  the 
precious  metals.1 

1  G.  F.  Becker,  "  Notes  on  the  Early  Cretaceous  of  California,"  Amer. 
Jour.  Sci.,  iii.,  II.  201.  "  Antiquities  from  under  Tuolumne  Table  Moun- 
tain, California,"  G.  S.  A.,  II.  189.  "Cretaceous  Metamorphic  Rocks  of 
California,"  Amer.  Jour.  Sci.,  iii.,  XXXI.  348.  "Structure  of  a  Portion 
of  the  Sierra  Nevada  of  California,"  G.  S.  A.,  II.  50.  "Notes  on  the 
Stratigraphy  of  Calirornia,"  Bull  19,  U.  S.  Geol.  Survey.  W.  P.  Blake, 
"  Notes  on  California,"  Amer.  Jour.  Sci.,  ii.,  XVIII.  441.  W.  H.  Brewer 
epitomizes  Whitney's  report,  Amer.  Jour.  Sci.,  ii.,  XLI.  231;  also  351.  J. 
D.  Dana,  "Notes  on  Upper  California,"  Amer.  Jour.  Sci.,  ii.,  VII.  376. 
J.  S.  Diller,  "  Geology  of  the  Lassen  Peak  District,"  Eighth  Ann.  Eep.  Di- 


242 


KEMP'S    ORE  DEPOSITS. 


2.12.07.  Calico  District.  Deposits  of 
silver  chloride  in  fissure  veins,  small  frac- 
tures and  pockets  in  liparites  and  tuf aceous 
sandstones,  probably  of  the  Pliocene  series. 
They  occur  in  southwestern  California,  in 
that  portion  of  the  State  belonging  rather 
to  the  Great  Basin  than  to  the  Pacific 
slope.  An  immense  outbreak  of  liparite 
has  formed  a  series  of  elevations,  and  the 
attendant  tufas  are  extensively  developed. 


':ui.  '•'•'•*'•'• 


rector  U.  S.  Geol.  Survey,  pp.  401,  435.  "On 
the  Cretaceous  Rocks  of  Northern  California," 
Amer.  Jour.  Sci.,  iii.,  XL.  476.  "  On  the  Geol- 
ogy  of  Northern  California,"  Proc.Phil.  Soc.  of 
Wash.,  Jan.  16,  1886;  Abstract.  Amer.  Jour. 
Sri.,  iii.,  XXXIII.  152.  "  Geology  of  the  Tay- 
lorville  Region,  Plumas  County,"  BulL  Geol. 
Soc.  Amer.,  III.  369.  G.  K.  Gilbert,  "The  Re- 
cency  of  Certain  Volcanoes  of  the  Western 
United  States,"  A.  A.  A.  S.,  XXIII.  29.  A. 
Hyatt,  "Jura  and  Trias  of  Taylorville,  Cali- 
fornia,"  Bull.  Geol.  Soc.  Amer. ,  III.  395.  Will- 
iamlrelan,  State  Mineralogist,  Ann.  Rep.,  1886, 
and  following,  especially  1890,  geology  by 
counties.  J.  Leconte,  "Post-tertiary  Ele- 
vation  of  the  Sierra  Nevadas,  shown  by  the 
River  Beds,"  Amer.  Jour.  Sri.,  iii.,  XXXII.  167. 
"Old  River  Beds  of  California,"  Ibid.,  iii., 
XIX.  190  ;  iii ,  XXXVIII.  261.  "  Extinct  Vol- 
canoes  about  Lake  Mono,  and  their  Relations 
to  the  Glacial  Drift,"  Ibid.,  iii.,  XVIII.  35. 
Jules  Marcou,  "Report  on  the  Geology  of  a 
Portion  of  Southern  California,"  Wheeler's  Sur- 
vey,Ann.  Rep.,  1876,  App.,  p  158.  J.  E.  Mills, 
"  Stratigraphy  and  Succession  of  the  Rocks  of 
the  Sierra  Nevada  of  California,"  BulL  Geol. 
Soc.  Amer.,  III.  413.  E.  Reyer,  Theoretische 
Geologic,  p.  537,  1888.  I.  C.  Russell,  "The 
Quaternary  History  of  Mono  Valley,  CUi- 
fornia,"  Eighth  Ann.  Rep.  Director  U.  S.  Geol. 
Survey,  pp.  267-400.  H.  W.  Turner,  "The 
Geology  of  Mount  Diablo,  with  the  Chemistry 
of  the  Rocks,  by  W.  H.  Melville,"  G.  S.  A.,  II. 


THE  PACIFIC  SLOPE. 


243 


The  ore  is  thought  by  Lindgren  to  have  come  in  heated  solution 
from  below  and  to  have  filled  the  fissures  and  overflowed,  forming 
the  surface  deposits  in  the  tufas.  (Cf.  Silver  Cliff,  Colorado.) 
There  are  deposits  of  gold  ores  in  the  same  region.1 

2.12.08.  Example  44.  Auriferous  Gravels.  (1)  River  grav- 
els, or  placers  in  the  beds  of  running  streams.  These  have  been 
often  referred  to  in  other  States,  but  the  type  is  placed  in  Cali- 


FlG,  59.— View  of  the  Union  diggings,  Columbia  Hill,  Nevada  County, 
California.    From  a  photograph. 

fornia,  as  they  are  there  best  known.  They  were  the  first  gravels 
washed  in  1849,  and,  although  substantially  exhausted  by  1860, 
were  very  productive.  Eastward  from  the  great  Sacramento 


383.  J.  A.  Veatch,  "Notes  on  a  Visit  to  the  Mud  Volcanoes  of  the  Col- 
orado Desert,"  etc.,  Amer.  Jour.  Sci.,  ii.,  XXVI.  288.  J.  D.  Whitney  and 
others,  reports  of  the  California  Geological  Survey,  issued  at  Cambridge, 
Mass.  L.  G.  Yates,  "Notes  on  the  Geology  and  Scenery  of  the  Islands 
forming  the  Southern  Line  of  the  Santa  Barbara  Channel,"  A.  G.,  V.  43. 

1  W.  Lindgren,   "The  Silver  Mines  of  Calico  District,  California," 
M.  E.,  XV.  717. 


244 


KEMP'S    ORE  DEPOSITS. 


Valley  the  surface  rises  with  a  quite  gentle  gradient  to  the  sum- 
mit of  the  Sierras.  The  country  consists  chiefly  of  metamorphic 
rocks,  which  have  yielded  a  very  few  well-determined  fossils  of 
Carboniferous,  Jurassic,  and  Cretaceous  ages  ;  but  the  identity  of 


« .»    --v/^*^;  ••*•-.        -""^y -'.:..  •»-*• 


FIG.  60.— View  of  the   Timbuctoo  diggings,    Yuba  Comity,    California. 
From  a  photograph. 


the  strata  in  all  the  stretch  is  difficult  to  make  out,  because  where 
the  fossils  were  originally  present  they  are  almost  entirely  de- 
stroyed by  metamorphism.  Down  the  slopes  of  the  range  the 
modern  streams  have  flowed  and  cut  deep  canons  in  which  gravels 
have  gathered.  Out  in  the  more  open  country  the  gravels  have 
also  accumulated  and  have  furnished  some  productive  bars.  The 


THE  PACIFIC  SLOPE.  245 

gold  has  been  derived  principally  from  the  quartz  veins  of  the 
slates,  which  are  later  described,  and  has  been  mechanically  con- 
centrated in  the  streams.  Before  coming  to  its  final  rest  it  may 
have  lodged  in  the  high  or  deep  gravels,  of  which  mention  will 
next  be  made. 

It  is  accompanied  by  magnetite  as  a  general  thing,  by  zircon, 
garnet,  and  rarely  by  other  heavy  metals,  such  as  platinum  and 
iridosmine.  The  greatest  amount  is  usually  near  the  bed  rock, 
and  when  this  is  at  all  porous  the  gold  may  work  into  it  to  a  small 
distance  from  the  top.  The  gold  is  usually  in  flattened  pellets  of 
all  sizes,  from  the  finest  dust  to  nuggets  of  considerable  weight. 
They  show  evidence  of  being  water  worn.  The  interesting  phe- 
nomena connected  with  the  possible  circulation  of  the  precious 
metal  in  solution  through  the  gravels  are  discussed  under  the  deep 
gravels.  Important  deposits  of  the  same  general  character  as  these 
have  also  been  dug  over  near  Santa  Fe,  N.  M.  ;  in  California 
Gulch,  near  Leadville,  Colo.;  at  Fairplay,  Colo.;  in  San  Miguel 
County,  Colorado  ;  in  the  Sweetwater  district,  Wyoming  ;  near 
Butte,  Mont.  ;  in  Last  Chance  and  Prickly  Pear  gulches,  near 
Helena,  Mont.;  in  the  Black  Hills;  in  southern  Idaho,  especially 
along  the  Snake  River  ;  and  at  various  points  in  Washington  and 
Oregon.  Placers  of  this  type  have  also  been  found  on  the  slopes 
of  the  Green  Mountains  and  in  the  Southern  States,  but  they  never 
have  proved  of  serious  importance. 

2.12.09.  (2)  High  or  Deep  Gravels.  With  the  exhaustion  of 
the  river  gravels  the  gold  seekers  of  California  were  driven  to 
prospect  on  the  higher  slopes,  where  auriferous  gravels  much  less 
accessible  had  been  long  noted.  Increasing  observation  and  de- 
velopment have  shown  that  these  are  the  relics  of  a  former  and 
very  extensive  drainage  system,  which  was  more  or  less  parallel 
with  the  present  streams,  but  of  greater  volume.  The  beds  lie  in 
deep  gulches  in  the  slates,  and  are  capped  in  most  cases  by  basal- 
tic lava  flows  or  by  consolidated  volcanic  tuffs,  called  cement. 
They  extend  some  250  miles  along  the  Sierras  and  up  to  5000  feet 
above  the  sea.  They  have  at  times  great  thickness,  reaching  600 
feet  at  Columbia  Hill,  but  drop  elsewhere  to  1  or  2  feet.  They  vary 
from  a  maximum  width  in  workable  material  of  1000  feet  to  a  mini- 
mum of  150.  The  inclosing  slates  on  the  sides  of  the  old  river 
valley  are  called  "  the  rims,"  and  on  them  are  sometimes  found 
other  gravels.  In  some  districts  channels,  belonging  to  two  or 
three  periods  of  flow,  have  been  traced.  They  tend  to  follow  the 


246 


KEMP'S    ORE  DEPOSITS. 


softer  strata,  breaking  at  times  across  the  harder  rocks.  The 
channel  filling  consists  of  gravel,  sand,  and  clays,  volcanic  tuffs, 
and  firm  basalt.  With  these  are  great  quantities  of  silicified 
trees,  and  even  standing  trunks  project  through  some  beds.  The 
gravel  is  oftenest  formed  of  white  quartz  boulders,  but  may  con- 
tain all  the  metamorphic  rocks  of  the  neighborhood,  and  even 
boulders  brought  from  a  great  distance.  The  gravel  at  times  is 
cemented  together  by  siliceous  and  calcareous  matter,  and  then 
requires  blasting ;  but  loose  gravel  also  occurs.  The  clays  are 
locally  called  "pipe  clays,"  and  are  often  interbedded  with  sand 
layers.  They  are  blue  when  unoxidized,  giving  rise  to  the  term 
"  blue  lead,"  but  red  oxidized  clays  are  not  infrequent.  The  clays 


FIG.  61. — Generalized  section  of  a  deep  gravel  bed,  with  technical  terms. 
After  H.  E.  Browne,  Rep.  Cal.  State  Mineralogist,  1890,  p.  437. 

contain  many  leaf  impressions  of  species  thought  by  Lesquereux  to 
be  late  Tertiary.  The  gravels  also  contain  bones  of  extinct  verte- 
brates, and  have  afforded  some  authentic  human  remains  and 
stone  implements  of  good  workmanship.  The  volcanic  tuffs  have 
been  strong  factors  in  modifying  the  original  drainage  lines. 
They  have  flowed  into  the  ancient  valleys  in  a  state  of  mud  and 
have  then  consolidated. 

2.12.10.  The  richest  gravels  are  those  nearest  the  bed  rock. 
In  these  the  distribution  of  the  gold  is  governed  more  or  less  by 
the  character  of  the  ancient  channels.  It  favors  the  inside  of 
bends  and  the  tops  of  steeper  runs.  The  gradients  of  the  old 
channels  were  fairly  high,  often  running  100  to  200  feet  per  mile. 
Gold  has  also  been  found  by  assay  in  pyrite  that  has  been  formed 
in  the  gravels  since  their  deposition,  and  from  this  it  is  evident 
that  the  precious  metal  does  circulate  in  solution  with  sulphate  of 


THE  PACIFIC  SLOPE. 


247 


iron,  but  on  this  slender  foundation  some  quite  unwarranted 
chemical  hypotheses  for  the  origin  of  nuggets  have  been  based. 
Substantially  all  the  gold  has  been  derived  by  the  mechanical 
degradation  of  the  quartz  veins  in  the  slate. 

2.12.11.  The  depths  to  which  the  modern  streams  have  cut  out 
their  channels  below  the  old  drainage  lines  have  received  con- 
siderable attention.  Whitney  avers  that  no  disturbance  has  taken 
place  since  the  old  gravels  were  laid  down,  but  Leconte  thinks 
that  there  has  been  a  tilting  or  elevation  of  the  higher  parts  of 
the  range,  all  moving  as  a  block.  Becker  has  recently  shown  in  the 


5000 


19    ZO   l\    ZZ    23   Z.4-  £5   2627 


FIG.  62. — Section  of  Forest  Hill  Divide,  Placer  County,  California,  to  il- 
lustrate the  relations  of  old  and  modern  lines  of  drainage.    After 
R.  E.  Browne,  Rep.  Cal.  State  Mineralogist,  1890,  p.  444. 


high  portions  a  great  series  of  small  north  and  south  faults  with 
uniform  downthrow  on  the  western  side  or  upthrow  on  the  east- 
ern. (See  paper  below,  cited  from  Geological  Society  of  America.) 
This  is  of  varied  intensity  in  different  portions  and  is  limited  to 
the  strip  just  west  of  the  summit.  It  occurred  in  the  Pliocene 
and  increased  the  gradient  of  the  streams  where  the  present  deep 
canons  occur,  but  had  no  effect  near  the  plains,  where  the  old  and 
new  channels  are  nearly  on  the  same  level. 

2.12.12.  After  the  formation  of  the  deep  gravels  and  after  the 
volcanic  flows,  glaciation  took  place  in  great  extent  over  the 
mountain  sides,  but  it  was  doubtless  later  in  time  than  the  glacial 
period  of  the  East.  References  to  the  similar  great  development 
of  the  ice  in  Washington  have  already  been  made.  Many  hypoth- 
eses were  early  advanced  to  explain  the  deep  gravels.  They 


248  KEMP'S   ORE  DEPOSITS. 

have  been  referred  to  the  ocean,  to  ocean  currents,  and  to  glaciers  ; 
but  it  is  now  well  established  that  they  are  river  gravels,  formed 
when  the  rainfall  was  probably  in  excess  of  what  it  is  to-day,  and 
when  the  attitude  of  the  land  toward  the  ocean  may  have  been 
different.1 

2.12.13.  Example  45.  Gold  Quartz  Veins.  Veins  of  gold- 
bearing  quartz,  usually  described  as  segregated  veins,  in  slates 
and  other  metamorphic  rocks,  and  more  or  less  parallel  with  the 
bedding.  The  quartz  contains  auriferous  pyrite,  free  gold, 
arsenopyrite,  chalcopyrite,  tetrahedrite,  galena,  and  blende,  but 
pyrites  is  far  the  most  abundant.  Some  tellurides  have  been 
noted  by  Silliman  at  Carson  Hill,  Calaveras  County.  The  veins 
approximate  at  times  a  lenticular  shape,  which  is  less  marked  in 
California  than  in  some  other  regions,  and  which  shows  analogies 
of  shape  with  pyrites  lenses  (Example  16)  and  magnetite  lenses 
(Example  12).  In  such  cases  the  fissure-vein  character  is  some- 


1  G.  F.  Becker,  "  Notes  on  the  Stratigraphy  of  California,"  Bull  19, 
U  S.  GeoL  Survey.  "  Structure  of  the  Sierra  Nevadas,"  G.  S.  A.,  II.  43. 
W.  P.  Blake,  "  The  Various  Forms  in  which  Gold  Occurs,"  Re}).  Director 
of  the  Mint,  1884,  p.  573.  A.  J.  Bowie,  Jr.,  "Hydraulic  Mining  in  Cali- 
fornia," M.  E.,  VI.  27.  R.  E.  Browne,  "  The  Ancient  River  Beds  of  the 
Forest  Hill  Divide,"  Rep.  Col.  State  Mineralogist,  1890,  p.  435.  RPC.  T. 
Egleston,  "Formation  of  Gold  Nuggets  and  Placer  Deposits,"  M.  E.,  IX. 
63.  "Working  Placer  Deposits  in  the  United  States,"  School  of  3fiu.es 
Quarterly,  VII.,  p.  101.  J.  H.  Hammond,  "Auriferous  Gravels  of  Cali- 
fornia," Rep.  Director  of  the  Mint,  1881,  p.  616.  Rec.  Rep.  Cal.  State 
Mineralogist,  1889,  p.  105.  H.  G.  Hanks,  "Placer  Gold,"  Rep.  Director 
of  the  Mint,  1882,  p.  728.  H.  G.  Hanks  and  William  Irelan,  Rep.  Cal.  State 
Mineralogist,  Annual.  T.  S.  Hunt,  "On  a  Recent  Formation  of  Quartz, 
and  on  Silicification  in  California,"  Engineering  and  Mining  Journal,  May 
29,  1880,  369.  J.  Leconte,  "The  Old  River  Beds  of  California,"  Amer. 
Jour.  Sci.,  iii.,  XIX.  80,  p.  176.  J.  J.  McGillivray,  "The  Old  River  Beds 
of  the  Sierra  Nevada  of  California,"  Rep.  Director  of  the  Mint,  1C81,  p. 
630.  R.  I.  Murchison,  "  Siluria,"  etc.  Contains  a  sketch  of  the  distribu- 
tion of  gold  over  the  earth.  J.  S.  Newberry,  "  On  the  Genesis  and  Distri- 
bution of  Gold,"  School  of  Mines  Quarterly,  Vol.  III.;  Engineering  and 
Mining  Journal,  Dec.  24  and  3^  1881.  J.  A.  Phillips,  "  Notes  on  the 
Chemical  Geology  of  the  California  Gold  Fields,"  Philos.  Mag.,  Vol. 
XXXVI.,  p.  3^1 ;  Proc.  Roy.  Soc.,  XVI.  294 ;  Amer.  Jour.  Sci.,  ii.,  XL VII. 
134.  B.  S  lliman,  "On  the  Deep  Placers  of  the  South  and  Middle  Yuba, 
Nevada  County,  California,"  Amer.  Jour.  Sci.,  ii.,  XL.  1.  J.  D.  Whitney, 
"Auriferous  Gravels  of  the  Sierras/'  Cambridge,  1880.  "Climatic  Changes 
in  Later  Geological  Times,"  Cambridge. 


THE  PACIFIC  SLOPE.  249 

what  obscure.  In  California  the  veins  occupy  undoubted  fissures 
in  the  slates.  The  largest  and  best  known  is  the  so-called  Mother 
Lode,  which  is  a  lineal  succession  of  innumerable  larger  and 
smaller  quartz  veins  that  run  parallel  with  the  strike,  but  which 
cut  the  steep  dip  of  the  slates  at  an  angle  of  10°.  It  was  doubt- 
less formed  by  faulting  in  steeply  dipping  strata.  The  wall  rocks 
of  the  California  veins  are  serpentine,  diabase,  diorite,  and  granite, 
as  well  as  slate,  for  all  these  enter  into  the  western  slopes  of  the 
Sierras.  The  serpentine  is  probably  a  metamorphosed  igneous 
rock,  while  the  diabase  and  diorite  form  great  dikes.  Considerable 
calcite,  dolomite,  and  ankerite  occur  with  the  quartz,  and  very 
often  it  is  penetrated  by  seams  of  a  green  chloritic  silicate,  which 
is  provisionally  called  mariposite,  as  it  is  probably  not  a  definite 
mineral,  but  rather  an  infiltration  of  decomposition  products.  The 
quartz  veins  vary  somewhat  in  appearance,  being  at  times  milk 
white  and  massive  (locally  called  "  hungry,"  from  its  general  bar- 
renness), at  times  greasy  and  darker,  and  again  manifesting  other 
differences,  which  are  difficult  to  describe,  although  more  or  less 
evident  in  specimens.  The  richer  quartz  in  many  mines  is  some- 
what banded,  and  is  called  ribbon  quartz.  The  quartz  has  been 
studied  in  thin  sections,  especially  in  rich  specimens,  by  W.  M. 
Courtis,  who  shows  that  fluid  or  gaseous  inclusions  of  what  is 
probably  carbonic  acid  are  abundant.  In  rich  specimens  the  cavi- 
ties tend  to  be  more  numerous  than  in  poor,  but  more  data  are 
needed  to  form  the  basis  of  any  reliable  deductions.  Some  quartz 
showed  evidence  of  dynamic  disturbances.  The  walls  of  the  veins 
are  .themselves  impregnated  with  the  precious  metal  and  the  at- 
tendant sulphides.  The  rich  portions  of  the  veins  occur  in  chutes 
to  a  large  degree. 

2.12.14.  The  great  Mother  Lode  is  the  largest  group  of  veins 
in  California.  It  extends  112  miles  in  a  general  northwest  direc- 
tion. Beginning  in  Mariposa  County,  in  the  south,  it  crosses 
Tuolumne,  Calaveras,  Amador,  and  El  Dorado  counties  in  succes- 
sion. It  is  not  strictly  continuous  nor  is  it  one  single  lode,  but 
rather  a  succession  of  related  ones,  which  branch,  pinch  out,  run 
off  in  stringers,  and  are  thus  con^lex  in  their  general  grouping. 
Over  500  patented  locations  have  been  made  on  it.  Whitney  has 
thought  it  may  have  originated  from  the  silicification  of  beds  of 
dolomite,  but  others  regard  it,  with  greater  reason,  as  a  great 
series  of  veins  along  a  fissured  strip.  The  veins  are  often  left  in 
strong  relief  by  the  erosion  of  the  wall  rock,  and  thus  are  called 


250  KEMP'S  ORE  DEPOSITS. 

ledges,  or  reefs.  Some  discussion  has  arisen  over  the  condition  of 
the  gold  in  the  pyrite,  but  in  most  cases  it  is  the  native  metal 
mechanically  mixed,  and  not  as  an  isomorphous  sulphide.  It  has 
been  detected  in  the  metallic  state,  in  a  thin  section  of  a  pyrite 
crystal  from  Douglass  Island,  Alaska,  as  later  set  forth  (2.13.04), 
and  the  fact  that  it  remains  as  the  metal  when  the  pyrite  is  dis- 
solved in  nitric  acid  makes  this  undoubtedly  the  general  condition. 
The  association  of  gold  with  bismuth,  which  has  been  shown  by 
R.  Pearce  to  occur  in  the  sulph'urets  of  Gilpin  County,  Colorado 
(referred  to  on  p.  212),  and  the  difficulty  experienced  in  amalga- 
mating some  ores,  indicate  the  possibility  of  other  combinations. 
When  crystallized,  gold  has  shown,  in  one  specimen  and  another, 
nearly  all  the  holohedral  forms  of  the  isometric  system,  but  the 
octahedron  and  rhombic  dodecahedron  are  commonest.  The  veins 
are  younger  than  any  of  the  igneous  dikes  with  them.  They  may 
have  been  filled,  as  thought  by  Whitney,  during  the  metamor- 
phism  of  the  rocks  attendant  upon  their  upheaval  in  post-Jurassic 
time.  Certain  it  is  that  a  very  extensive  circulation  of  siliceous 
solutions  was  in  progress.  For  the  gold  in  the  similar  veins  of 
Australia  a  precipitation  by  organic  matter  has  been  urged.  (See 
William  Nicholas,  "The  Origin  of  Gold  in  Certain  Victorian 
Reefs,"  Engineering  and  Mining  Journal,  Dec.  15,  1883.)  In 
the  development  of  explanations  of  origin,  however,  a  wide  field 
for  study  yet  remains.1 


1  M.  Attwood,  "  On  the  Wall  Rocks  of  California  Gold  Quartz  and  the 
Source  of  the  Gold,"  Rep.  Cal.  Mineralogist,  1888,  p.  771  (thought  to  be 
due  to  igneous  injection  in  diabase).  W.  P.  Blake,  "On  the  Parallelism 
between  the  Deposits  of  Auriferous  Drift  of  the  Appalachian  Gold  Field 
and  those  of  California,"  Amer.  Jour.  Set.,  ii.,  XXVI.  128.  "Remarks 
on  the  Extent  of  the  Gold  Region  of  California  and  Oregon,"  etc.,  Ibid. 
ii.,  XX.  72.  "The  Carboniferous  Age  of  a  Portion  of  the  Gold-bearing 
Rocks  of  California,"  Ibid.,  ii.,  XLV.  264.  W.  H.  Brewer,  reply  to  above, 
Ibid.,  ii.,  XLV.  397.  A.  Bowman,  "  Geology  of  the  Sierra  Nevada  in  Re- 
la^ion  to  Vein  Mining,"  Min.  Resources  West  Rocky  Mountains,  1875,  p. 
441.  W.  H.  Brewer,  "  On  the  Age  of  the  Gold  bearing  Rocks  of  the  Pacific 
Coast,"  Amer.  Jour.  Sci.,  ii.,  XLII.  114.  F.  G.  Corning,  "The Gold  Quartz 
Mines  of  Grass  Valley,  California,"  Engineering  and  Mining  Journal, 
D.  c.  11,  1886,  p.  418.  W.  M.  Courtis,  «•  Gold  Quartz,"  M.  E.,  1889,  Ottawa 
meeting.  H.  W.  Fairbanks,  "  Geology  of  the  Mother  Lode,"  Tenth  Ann. 
Rep.  Cal.  Mineralogist;  also  in  briefer  form  in  Amer.  GeoL,  April,  1891, 
p.  201.  Rec.  "On  the  Pre-Cretaceous  Rocks  of  the  California  Coast 
Ranges,"  Amer.  GeoL,  March,  1892,  February,  1893.  J.  H.  Hammond, 


THE  PACIFIC  SLOPE.  251 

"Mining  of  Gold  Ores  in  California,"  Tenth  Ann.  Rep.  State  Mineralogist, 
p,  852.  Rec.  P.  Laur,  "Du  Gisement  et  de  1'Exploration  de  1'Or  en  Cali- 
fornie,"  Ann.  des  Mines,  Vol.  III.,  1863,  p.  412.  G.  W.  Maynard,  "Re- 
marks on  Gold  Specimens  from  California,"  M.  E.,  VI.  451.  J.  S.  New- 
berry,  "  On  the  Genesis  and  Distribution  of  Gold,"  School  of  Mines  Quar- 
terly, III.,  p.  16.  A.  Remond,  "Mining  Statistics,"  No.  1,  Cal.  Geol. 
Survey  (tabular  statement  of  quartz  mining  and  mills  between  the  Merced 
and  Stanislaus  rivers).  J.  A.  Phillips,  "Mining  and  Metallurgy  of  Gold 
and  Silver,"  Wiley,  N.  Y.;  also  treatise  on  Ore  Deposits,  p.  524.  Rec. 
C.  M.  Rolker,  "  The  Late  Operations  in  the  Mariposa  Estate,"  M.  E.,  VI. 
145.  B.  Silliman,  "Notice  of  a  Peculiar  Mode  of  Occurrence  of  Gold  and 
Silver  in  the  Foothills  of  the  Sierra  Nevada,  California,"  Amer.  Jour.  Sci., 
ii.,  XLV.  92;  Cal.  Aead.  Sci.,  Vol.  III.,  p.  353.  H.  M.  Turner,  review  of 
recent  papers  by  H.  W.  Fairbanks  and  others  on  California  geology,  in 
Amer.  Geol.,  June,  1893.  Rec.  J.  D.  Whitney,  Cal.  Geol.  Survey,  Geol- 
ogy, Vol.  I.,  p.  212.  J.  S.  Wilson,  "On  the  Gold  Regions  of  California," 
Quar.  Jour.  Geol.  Sci.,  Vol.  X.,  p.  308,  1854. 


CHAPTER   XIII. 

GOLD  ELSEWHERE  IN  THE  UNITED  STATES  AND  IN  CANADA. 

2.13.01.  Example  45«.  Southern  States.  (1)  Gold  quartz 
veins  (segregated  veins)  in  metamorphic  slates,  talcose  schists, 
etc.,  of  late  Archaean  or  early  Paleozoic  age,  with  numerous  as- 
sociated trap  (diabase)  dikes.  (2)  Beds  of  auriferous  slates,  gneiss, 
feldspathic  and  hydromica  schists,  and  even  limestone.  The 
general  geology  of  the  southern  Atlantic  States  has  been  outlined 
in  the  introduction.  Reference  may  again  be  made  to  the  Coastal 
Plain  of  Quaternary,  Tertiary,  and  Mesozoic  rocks,  and  to  the 
Archaean  strip  back  of  this.  In  the  latter  are  found  the  gold  de- 
posits. At  times  they  resemble  the  Western  quartz  veins,  but  they 
are  also  extremely  diverse  in  character,  and  involve  almost  every 
sort  of  rock.  Gold  has  even  been  found  in  a  trap  dike  by  Genth. 
It  is  generally  in  pyrite,  and  the  rock,  where  productive,  is  heavily 
charged  with  this  mineral.  The  trap  dikes  have  also  exerted  an 
important  influence,  and  in  some  localities,  as  at  the  Haile  mines, 
South  Carolina,  the  rock  is  rich  only  near  them.  They  have 
probably  stimulated  the  ore-bearing  solutions.  The  belt  of  aurif- 
erous rocks  begins  in  Maryland,  although  gold  is  known  in  the 
States  farther  north.  It  runs  with  varying  width  into  Alabama, 
where  it  terminates.  It  reaches  a  maximum  of  70  miles  in  North 
Carolina.  The  country  rock  in  these  unglaciated  regions  is  often 
covered  to  a  great  depth  by  the  residual  clays  and  other  products 
of  its  alteration.  These  are  as  much  as  100  feet  in  places.  This 
material  is  sometimes  called  laterite.  Where  the  original  rocks 
have  been  auriferous  it  has  furnished  loose  material  for  panning 
and  washing,  which  is  essentially  different  from  the  Western 
placers.  It  gradually  works  down  hill,  and  has  been  called  by 
Kerr  "frost  drift."  The  ores  of  the  Southern  States  are  gen- 


. 

GOLD  ELSEWHERE  IN  UNITED  STATES  AND  CANADA.     253 

erally  low  grade,  and  need  careful  management  to  be  made  profit- 
able.1 

2.13.02.  Example  45b.    Ishpeming,  Mich.    In  the  metamorphic 
rocks  of  the  iron-bearing  areas  in  the  Lake  Superior  region  gold- 
bearing  quartz  veins  have  been  discovered  and  several  mines  have 
been  opened.     The  Ropes  mine  is  the  best  known  and  has  yielded 
some  good  ore.2 

ALASKA. 

2.13.03.  Geology. — Our  knowledge  of  the  geology  of  Alaska  is 
very  fragmentary,  and  is  chiefly  obtained  from  the  reports  of  ex- 
ploring expeditions  along  the  coast  and  up  the  Yukon  River.    The 
Cretaceous  and    Tertiary   rocks    of   Washington    and  of   British 
America  extend  north  into  the  southern  portion.     Igneous  rocks 

1  W.  P.  Blake,  A.  Eaton,  D.  Olmstead,  C.  U.  Shepard,  the  elder  Silli- 
man,  and  others  have  made  many  references  to  gold  in  the  Southern  States 
in  the  early  numbers  of  the  American  Journal  of  Science.     H.  M.  Chance, 
"  Auriferous  Gravels  of  North  Carolina,"  Amer.  Philos.  Soc.,  July  15, 1881, 
p.  477.    H.  Credner,  "  Report  of  Explorations  in  the  Gold  Fields  of  Virginia 
and  North  Carolina,"  Amer.  Jour,  of  Mining,  1868,  pp.  361,  377,  393,  407.     W. 
B.  Devereux,  "  Gold  and  its  Associated  Minerals  at  Kings  Mountain,  North 
Carolina,"  Engineering  and  Mining  Journal,  Jan.  15,  1881,  p.  39.    S.  F. 
Emmons,  "Notes  on  the  Gold  Deposits  of  Montgomery  County,  Mary- 
land," June  11,  1881,  p.  397.     F.  A.  Genth,  "Contributions  to  Mineralogy," 
Amer.  Jour.  Sci.,  ii.,  XXVIII.  246.     F.  C.  Hand,  "  Southern  Gold  Fields," 
Engineering  and  Mining  Journal,  Dec.   7,  1889,  p.  495.     G.  B.  Hanna, 
"  Fineness  of  Native  Gold  in  the  Carolinas  and  Georgia,"  Ibid.,  Sept.  18, 
1886,  p.  201.     W.  C.  Kerr,  "  Gold  Gravels  of  North  Carolina,"  M.  E.,  VIII. 
462.     "Some  Peculiarities  in  the  Occurrence  of  Gold  in  North  Carolina," 
M.  E.,  X.  475  ;  also  Geological  Report  on  North  Carolina,  1875.     O.  M. 
Lieber,  "  Ueber  das  Gold-vorkommen  in  North  Carolina,"  Gangstudien, 
Vol.  III.,  p.  253.     Lieber  states  that  Whitney's  Metallic  Wealth  was  writ- 
ten to  "boom "  certain  mines  !     " Gold  in  South  Carolina,"  Gangstudien, 
'Vol.  Ill:,  pp.  253,  481.     P.  H.  Mell,  "  Auriferous  Slate  Deposits  in  South- 
ern Mining  Regions,"   M.  E.,  IX.   399.      W.   B.  Phillips,    "The  Lower 
Gold  Belt  of  Alabama,"  Bull.   No.   3,  Geol  Survey  Ala.,  1892.     E.   G. 
Spillsbury,  "  Gold  Mining  in  South  Carolina,"  If.  E.,  XII.  99;  Engineer- 
ing and  Mining  Journal,  June  23,  1883,  p.  362.      A.  Thies  and  W.  B. 
Phillips,  "The  Thies  Process,  etc.,  at  the  Haile  Mine,  South  Carolina," 
M.  E.,  September,  1890.     A.  Thies  and  A.  Mezger,  "  Geology  of  the  Haile 
Mine,"  If.  E.,  September,  1890. 

2  C.  D.  Lawton,  Rep.  Mich.  Com.  of  Mineral  Statistics,  1887,  p.  167. 
"The  New  Michigan  Gold  Field,"  Engineering  and  Mining  Journal,  Sept. 
22,  1888,  p.  238.     M.  E.  Wadsworth,  Am.  Rep.  Mich.  State  Geologist,  is- 
sued January,  1892. 


254  KEMP'S   ORE  DEPOSITS. 

often  pierce  them.  Tertiary  coals  are  recorded  from  several  local- 
ities in  the  archipelago  in  the  southern  part.  The  Aleutian  Isl- 
ands mark  a  long  stretch  of  volcanic  eruptions.  W.  H.  Dall  has 
given  a  general  section  of  the  banks  of  the  Yukon  River  from 
the  British  boundary  to  the  delta.  There  are,  in  rough  order  from 
east  to  west,  granite,  talcose  slates,  and  Azoic  rocks,  150  miles  ; 
sandstone  and  conglomerate,  250  miles  ;  shales  with  one  small  coal 
seam,  75  miles  ;  blue  slate,  conglomerate,  eruptive  rocks,  slate, 
eruptive  rock,  blue  slate,  and  black  sandstone,  325  miles  ;  blue 
sandstone,  slate,  trap,  blue  and  black  slate,  volcanic  rock,  to  the 
northwest  mouth.  The  interior  is  largely  composed  of  tundras,  or 
great  plains  of  moss  and  other  plants,  frozen  into  perpetual  ice  at 
a  depth  of  a  foot  or  so.  These  hide  the  geology.  Doubtless  the 
slates  of  the  upper  waters  have  supplied  the  gold,  which  is  rich  in 
some  of  the  river  gravels.  On  the  Aleutian  Islands  some  brown 
Miocene  sandstones  are  seen  (Shumagin),  and  granite  and  meta- 
morphic  rocks.1 

2.13.04.  Example  46.  Douglass  Island.  A  dike  or  boss  of 
granite  400  feet  wide,  piercing  slates  regarded  as  Triassic  by  G.  M. 
Dawson,  and  impregnated  (i.e.,  the  granite)  with  auriferous  pyrites. 
This  enigmatical  ore  body  is  thought  by  Dawson  to  be  the  upper 
part  of  a  granite  dike.  It  consists  in  great  part  of  a  mass  of 
quartz,  feldspar,  calcite,  and  pyrite,  in  which  are  buried  the  so- 


1  "  Alaska  as  a  Mining  Territory,"  Engineering  and  Mining  Journal, 
June  27,  1885,  p.  444.  "Mineral  and  Agricultural  Wealth  of  Alaska,"  En- 
gineering and  Mining  Journal,  Aug.  24,  1887,  p.  134.  T.  A.  Blake,  Rep. 
on  the  Geol.  of  Alaska,  Ex.  Doc.  No.  177,  Fortieth  Congress,  New  Series, 
p.  314,  Washington,  1868.  W.  H.  Dall,  "Explorations  in  Alaska,"  Amer. 
Jour.  Sci.,  ii.,  XLV.  96.  Rec.  "Notes  on  Alaska  and  the  Vicinity  of 
Bering  Straits,"  Ibid.,  iii.,  XXI.  104.  "  Notes  on  Alaska  Tertiary  Deposits, 
Geological  Section  of  the  Shumagin  Islands,"  Ibid.,  iii.,  XXIV.  67.  "  Alaska 
and  its  Resources,"  Washington,  1870.  Rec.  "Glaciation  in  Alaska," 
Bull  Phil.  Soc.,  Vol.  VI.,  p.  33,  Washington,  1884.  G.  H.  Dawson,  "  Re- 
port on  the  Yukon  District  in  1887,"  Geol.  Survey  of  Canada,  1887-88, 
Vol.  III.,  Part  B,  pp.  14B-18B,  154B-156B.  H.  W.  Elliot,  "Our  Arctic 
Provinces,"  p.  163,  New  York,  1887.  E.  J.  Glave,  "Pioneer  Packhorses 
in  Alaska,"  The  Century,  September  and  October,  1892.  R.  G.  McConnell, 
"Glacial  Features  of  Parts  of  the  Yukon  and  Mackenzie  Basins,"  Geol. 
Soc.  of  Amer.,  I.,  p.  540.  I.  C.  Russell,  "  The  Surface  Geology  of  Alaska," 
Geol.  Soc.  of  Amer.,  I.,  p.  99.  E.  R.  Skidmore,  "Alaska,"  Rep.  Director 
of  the  Mint,  1883,  p.  17,  and  1884,  p.  17.  J.  Stanley-Brown,  "  Auriferous 
Sands  at  Yakutat  Bay,  Alaska,"  Nat.  Geog.  Mag.,  Vol.  III.,  1891. 


GOLD  ELSEWHERE  IN  UNITED  STATES  AND  CANADA.    255 

called  kernels,  which  have  been  shown  by  F.  D.  Adams  to  be  mass- 
es of  less  altered  granite,  almost  without  pyrite.  Both  varieties 
show  abundant  cataclastic  or  crushed  structure,  as  an  evidence  of 
having  suffered  from  dynamic  movements.  Adams  concludes  that 
the  mass  was  originally  a  hornblende  granite  that  has  been  sub- 
jected to  solfataric  action,  which  has  brought  in  the  gold.  The 
gold  in  itself  is  in  irregular  masses  in  the  pyrite.  The  Tread  well 
mine,  located  here,  is  very  extensive,  and  the  chief  source  of  Alaska, 
bullion.1 

2.13.05.  Example  45c.  Nova  Scotia.  The  southeastern  por- 
tion of  Nova  Scotia  is  composed  of  Cambrian  slates.  They  stretch 
from  Canso  to  Yarmouth,  and,  together  with  associated  granites, 
cover  from  6000  to  7000  square  miles.  There  are  two  well-marked 
divisions.  The  upper,  3000  feet  thick,  consists  of  dark  pyritous 
slates,  with  beds  of  quartzite  and  small  irregular  veins;  the  lower, 
8000  feet  thick,  has  quartzites,  sandstones,  and  slates,  which  in 
parts  contain  the  veins.  The  slates  are  folded  along  east  and 
west  axes.  The  veins  are  not  large,  averaging  from  4  to  8  inches, 
while  20  inches  is  very  exceptional.  The  gold  is  both  free  and 
associated  with  the  usual  sulphides,  among  them  often  mispickel. 
The  assays  are  not  high,  but  with  careful  working  the  mines  pay 
good  returns.2 

1  F.  D.  Adams,  "On  the  Microscopical  Character  of  the  Ore  of  the 
Tread  well  Mine,  Alaska,"  Amer.  GeoL,  August,  1889,  p.  88.     G.  M.  Daw- 
son,  "Notes  on  the  Ore  Deposits  of  the  Treadwell  Mine,  Alaska,"  Amer. 
Geol.,  August,  1889,  p.  84.     Mining  and  Scientific  Press,  San  Francisco, 
Sept.  27,  Oct.  4,  1884. 

2  J.  W.  Dawson,  "  On  Recent  Discoveries  of  Gold  in  Nova  Scotia," 
Canadian  Naturalist  and  Geologist,  December,  1861.     E.  Gilpin,  Jr.,  "The 
Nova  Scotia  Gold  Mines,"  M.  E.,  XIV.  674.     Rec.     H.  Y.  Hind,  "Report 
on  the  Mount  Uniache,  Oldhara,  and  Renfrew  Gold  Mining  District,"  Hali- 
fax, 1872  ;  Amer.  Jour.  Sci.,  iii.,  IV.  497.     D.  Honeyman,  "On  the  Geol- 
ogy of  the  Gold  Fields  of  Nova  Scotia,"  Quar.  Jour.  Geol.  Sci.,  Vol. 
XVIII.,  p.  342,  1862.     T.  S.  Hunt,  "On  the  Gold  Region  of  Nova  Scotia," 
Can.  Geol.  Survey,  1868 ;  Canadian  Naturalist,  February,  1868.     W.  E. 
Logun,  "  Notes  on  the  Gold  of  Eastern  Canada,"  Can.  Geol.  Survey,  1864.. 
O.  C.  Marsh,  "The  Gold  of  Nova  Scotia,"  Amer.  Jour.  Sci.,  ii.,  XXXII. 
395.    A.  Michel  and  T.  S.  Hunt,  "Report  on  the  Gold  Region  of  Canada," 
Can.  GeoL  Survey,  1866.     H.  S.  Poole,  "The  Gold  Leads  of  Nova  Scotia," 
Quar.  Jour.  Geol.  Sci.,  Vol.  XXXVI.,  p.  307.     A.  R.  C.  Selwyn,  "  On  the 
Gold  Fields  of  Quebec  and  Nova  Scotia,"  Can.  Geol.  Survey,  1870-  71,  pp. 
252-289.     B.  Symons,  "  The  Gold  Fields  of  Nova  Scotia,"  Trans.  Min*  As&o> 
and  Inst.  Cornwall,  III.  80,  1892. 


256  KEMP'S   ORE  DEPOSITS. 

2.13.06.  Example  45d     Gold  elsewhere  in  Canada.     At  the 
headwaters  of  the  Chaudiere  River,  in  eastern  Quebec,  auriferous 
gravels  have  been  located,  and  also  quartz  veins  in  the  metamor- 
phic  rocks.     They  have  been  worked  to  a  small  extent.     Gold  oc- 
curs in  many  places  north  and  west  of  Lake  Superior  in  the  region 
of  the  Lake  of  the  Woods.     Some  small  mining  has  been  carried 
on.     An  interesting  and  important  vein,  carrying  auriferous  mis- 
pickel  in  quartz,  occurs  in  Marmora,  Hastings  County,  just  north 
of  Lake   Ontario.      It  is   more  fully  described  under  "  Arsenic," 
as  it  is  the  one  American  source  of  that  metal.    Auriferous  gravels 
occur   in    British   Columbia    in  not  a  few  places   and  are  being 
worked.     They   are  also   found  along  the  disputed  boundary  of 
Alaska,  and  scattered  reports  of  their  existence  have  reached  civ- 
ilization from  the  Mackenzie  River  and  the  remote  Northwest.1 

2.13.07.  The  following  table  gives  an  idea  of  the  relative  im- 
portance of  the  several  States.     Full  details  of  the  United  States 
and  other  countries   are  given  in   the  Annual  Reports  of  the  Di- 
rector of  the  Mint,  the  Mineral  Resources  of  the  United  States 
Geological  Survey,  and  the  annual  statistical  number  of  the  En- 
gineering and  Mining  Journal. 

1881.  1890. 


Alaska  

Silver. 

Gold. 
$15,000 

Silver. 

$9,697 

Gold. 
$763,500 

Arizona  

$7,300,000 

1,060,000 

1,292,929 

1,000,000 

California    

750,000 

18,200,000 

1,163  636 

12,500  000 

Colorado 

.  .     .  .     17,160,000 

3,300,000 

24,307  070 

4  150  000 

Dakota 

70,000 

4  000  000 

129  292 

3  200  000 

Georeri  i    . 

125,000 

517 

100,000 

Idaho  

.    .     .  .     1,300,000 

1,700,000 

4,783,838 

1,850,000 

1  "  Descriptive  Catalogue  of  the  Economic  Minerals  of  Canada  at  the 
Colonial  and  Indian  Exhibition/'  London,  1886,  p.  54.  "  The  Marmora 
Gold  Mine,"  Engineering  and  Mining  Journal,  Oct.  23,  1880,  p.  266.  R. 
Bell,  "Mineral  Resources  of  the  Hudson  Bay  Territories,"  M.  E.,  Febru- 
ary, 1886.  E.  Coste, ' '  Report  on  the  Gold  Mines  of  the  Lake  of  the  Woods," 
Rep.  Prog.  Can.  Survey,  1882-84,  K,  3-22.  W.  M.  Courtis,  "  Animikie 
Rocks  and  their  Vein  Phenomena  as  shown  at  the  Duncan  Mine,  Lake  Su- 
perior," M.  E.,  XV.  671.  R.  W.  Ells,  "  Mining  Industries  of  Eastern  Que- 
bec," M.  E.,  October,  1889.  T.  S.  Hunt,  "On  Gold  in  the  Laurentian 
Rocks  of  Canada,''  A.  A.  A.  S.,  XVIIth  meeting.  A.  Michel  and  T.  S. 
Hunt,  "Report  on  the  Gold  Regions  of  Canada,"  Can.  Qeol.  Survey,  1866- 
68.  R.  P.  Roth  well,  "The  Gold-bearing  Mispickel  Vein  of  Marmora,  On- 
tario," M.  E.,  IX.  409. 


GOLD  ELSEWHERE  IN  UNITED  STATES  AND  CANADA.    257 


Silver. 
.  .  .  $2,630,000 

1881. 
Gold. 
$2,330,000 

Silver. 
$20,363,636 

1890. 
Gold. 
$3,300,000 

Nevada  

.  .  .     7,060,000 

2  250,000 

5,753,535 

2,800  000 

New  Mexico  

275,000 

185,000 

1,680,808 

850,000 

115,000 

7,757 

118,500 

50,000 

1,100,000 

96.969 

1,100,000 

35,000 

517 

100,000 

Utah..           

.     6,400,000 

145,000 

9  050,505 

680,000 

Washington 

120  000 

90  505 

204  000 

Other  States 

5  000 

20  000 

461  574 

130  000 

Total $43,000,000    $34,700,000 


$70,485,714    $32,845,000 


A  glance  at  the  table  will  indicate  where  the  heaviest  pro- 
ducers and  most  important  districts  are  situated.  In  the  next  few 
years  a  heavy  falling  off  in  silver  and  a  relative  increase  in  gold 
seems  inevitable. 


CHAPTER  XIY. 

THE  LESSER  METALS:    ALUMINIUM,   ANTIMONY,    ARSENIC, 
BISMUTH,   CHROMIUM,  MANGANESE. 

ALUMINIUM. 

2.14.01.  The  importance  of  aluminium  grows  with  improved 
and  cheaper  methods  of  production.  Its  sources  have  been  alums, 
either  natural  or  artificial,  corundum,  cryolite,  and  bauxite.  The 
first  of  these  is  formed  in  nature  by  the  decay  of  pyrite  in  shales 
and  slates,  and  is  little,  if  at  all,  used  at  present.  The  second  is 
now  more  valuable  as  an  abrasive.  Cryolite  (Al2F6.6NaF),  a  pe- 
culiar mineral,  occurring  in  quantity  only  in  Greenland,  has  been 
most  largely  employed  until  the  recent  discoveries  of  bauxite  have 
made  it  less  necessary.  The  cryolite  forms  an  immense  bed  or  vein 
in  gneiss  at  Evigtok,  on  the  Arksut  Fjord,  Greenland.1  Bauxite 
(A12O3.3H2O)  has  long  been  valuable  as  a  refractory  material,  but 
at  present  it  is  also  used  as  a  source  of  aluminium.  Bauxite  occurs 
in  quantity  in  several  of  the  Southern  States.  In  Floyd  County, 
Georgia,  it  covers  about  half  an  acre.  Near  Little  Rock,  Ark., 
it  is  in  greatest  quantity,  and  forms  an  interbedded  mass  in  fer- 
ruginous Tertiary  sandstone.  Small  amounts  of  oxide  of  iron 
partially  replace  the  alumina  at  times,  but  the  average  grade  is 
better  than  the  foreign.  It  is  considered  by  J.  F.  Williams  as 
probably  a  hot-spring  deposit,  but  the  origin  is  obscure.  Dis- 
covered deposits  aggregate  over  a  square  mile  and  range  up  to  40 
feet  thick.2 


1  G.  Hagermann,  "  On  Some  Minerals  associated  with  the  Cryolite  in 
Greenland,"  Amer.  Jour.  Sci. ,  ii. ,  XLII.  93.    J.  W.  Taylor,  "  On  the  Cryolite 
of  Evigtok,  Greenland,"  Quar.  Jour.  Geol.  Sci.,  XII.  140. 

2  J.  C.  Branner,  "Bauxite  in  Arkansas,"  Amer.  GeoL,  Vol.  VII.,  p. 
131,  1891.    Ann.  Rep.  GeoL  Survey  Arkansas,  1888,  Vol.  I.    J.  F.  Will- 
iams, Ann.  Rep.  Geol.  Survey  Arkansas,  1880,  Vol.  II.,  p.  124.     E.  Nichols, 
"  An  Aluminium  Ore,  Bauxite,"  M.  E.,  XVI.  905. 


THE  LESSER  METALS.  259 

ANTIMONY. 

Senarmontite,  Sb2O3 ;  Sb.  83.56  ;  O.  16.44. 

Stibnite   (Antimonite,    Antimony    Glance),    Sb2S3 ;    Sb.    71.8  ; 
S.   28.2. 

2.14.02.  Antimony  occurs  in  composition  with  several  silver 
ores,  but  almost  its  sole  commercial  source  is  stibnite.    The  oxide, 
senarmontite,  is  rarely  abundant  enough  to  be  an  ore.    Stibnite  was 
one  of  the  minerals  formerly  cited  as  having  originated  in  veins  by 
volatilization  from  lower  sources.    But  it  has  probably,  in  all  cases, 
been  derived  from  solutions  of  alkaline  sulphides. 

2.14.03.  Example   47.      Veins  containing  stibnite,  usually  in 
quartz  gangue.    California,  Kern  County.    At  San  Emigdio  a  vein 
of  workable  size  has  been  found.     It  has  a  quartz  gangue  and  is  in 
granite.     The  vein  varies  from  a  few  inches  to  several  feet  across, 
and  has  afforded  some  metal.     Several  others  are  known  in  San 
Benito  and  Inyo  counties. 

2.14.04.  Nevada,  Humboldt  County.    Stibnite  has  been  known 
for  some  years  in  veins  with  quartz  gangue.     The  Thies-Hutchens 
mines,  about  15  miles  from  Lovelock  station,   were  productive  in 
1891.      Lander  County.      The    most  important  of  the  American 
mines  are  the  Beulah  and  Genesee,  at   Big  Creek,  near  Austin. 
The  vein  is  reported  as  showing  three  feet  of  nearly  pure  stibnite. 
It  produced  700  tons  of  sulphide  in   1891,  and   was  operated  in 
1892. 

2.14.05.  Arkansas,  Sevier  County.     Stibnite  occurs   in  veins 
with   quartz  gangue  in  southwestern  Arkansas.     Some  attempts 
liave  been  made  to  develop  them,  but  the  ore  is  reported  to  be  too 
remote  for  profitable  working.     The  veins  appear  to  be  generally 
interbedded  in  Trenton   shales  and  to  lie   along  anticlinal  axes, 
which  trend  northeast.      They  are  all  controlled  by  the  United 
States  Antimony  Company  of  Philadelphia. 

2.14.06.  New  Brunswick,  York  County.     Veins   of  quartz  or 
quartz  and  calcite,  carrying  stibnite,  occur  over  several  square  miles. 
The  wall  rocks  are  clay  slates  and  sandstones  of  Cambro-Silurian 
age.     The  mines  have  been  commercially  productive.     The  veins 
vary  from  a  few  inches  to  six  feet. 

2.14.07.  Example  48.     Utah,  Iron  County.     Disseminations  of 
stibnite  in  sandstone  and  conglomerate,  following  the  stratification. 
In  Iron  County,  southwestern  Utah,  masses  of  radiating  needles 
occur   in   sandstones  and  between  the  boulders  of  an  associated 
conglomerate.     Very  large  individual  pieces  have  been  obtained, 


2 CO  KEMP'S   ORE  DEPOSITS. 

but  not  enough  for  profitable  mining.  Blake  thinks  that  the  ore 
has  crystallized  from  descending  solutions.  Eruptive  rocks  are 
present  above  the  sandstones. 

2.14.08.  An  interesting  deposit  of  senarmontite  was  worked 
for  a  time  in  Sonora,  just  south  of  the  Arizona  line,  but  it  was 
soon  exhausted.1 

ARSENIC. 

2.14.09.  This  metal  occurs  with  many  silver  ores  in  the  West 
and  in  arsenopyrite,  or  mispickel,  a  not  uncommon  arseno-sulphide 
in  the  gold  quartz  veins,  east  and  west.     At  the  Gatling  mines,  in 
the  town   of  Marmora   (more  lately   called  Deloro),  in  Hastings 
County,  Ontario,  auriferous  mispickel  occurs  in  great  quantity  in 
granite,  in  veins  with  quartz  gangue.     Considerable  oxide  of  arsenic 
has  been  obtained  in  the  past  from  the  roasters,  but  for  five  years 
or  more  the  mines  have  not  been  productive.     For  reference  to  the 
printed  descriptions  see  under  "Gold  in  Canada"  (2.13.07). 

BISMUTH. 

2.14.10.  Bismuth  occurs  with  certain  silver  ores  in  the  San 
Juan  district,  Colorado,  and  is  referred  to  in  describing  the  country 
under    "Silver   and  Gold"   (2.09.10).      Lane's    mine,  at  Monroe, 
Conn.,  has    furnished    museum    specimens    of    native  bismuth  in 
quartz.      Some  neighboring  parts  of  Connecticut    have    afforded 


1  General  references :  W.  P.  Blake,  "  General  Distribution  of  Ores 
of  Antimony,"  Mineral  Resources  of  the  U.  S.,  1883-84,  p.  641.  Arkan- 
sas:  T.  B.  Comstock,  Geological  Survey  of  Arkansas,  1888,  I.,  p.  136. 
F.  P.  Dunnington,  "  Minerals  of  a  Deposit  of  Antimony  Ores  in  Sevier 
County,  Arkansas,"  A.  A.  A.  S.,  1877.  Rec.  J.  W.  Mallet,  Chemical 
Neu-s,  No.  533.  C.  E.  Waite,  ''Antimony  Deposits  of  Arkansas,"  J\L  E., 
VII.  42,  C.  P.  Williams,  "  Notes  on  the  Occurrence  of  Antimony  in  Ar- 
kansas," M.  E.,  III.  150.  California  :  W.  P.  Blake,  "  Kern  County,"  U.  S. 
Pac.  R.  R.  Explorations  and  Survey,  Vol.  V.,  p.  291.  H.  G.  Hanks,  Rep. 
Col.  State  Mineralogist,  1884.  See  also  subsequent  reports  by  William 
Irelan,  Jr.  Mexico  :  E.  T.  Cox,  "  Discovery  of  Oxide  of  Antimony  in  So- 
nora," Amer.  Jour.  Sci.,  XX.  421.  J.  Douglass,  "The  Antimony  Deposit  of 
Sonora,"  Engineering  and  Mining  Journal,  May  21, 1881,  p.  350.  Nevada: 
Engineering  and  Mining  Journal,  1892,  p.  6.  New  Brunswick :  L.  W. 
Bailey,  "  Discovery  of  Stibnite  in  New  Brunswick,"  Amer.  Jour.  Sci.,  ii., 
XXXV.  150,  and  in  Rep.  on  the  Geol.  of  New  Brunswick,  1865  ;  also  H.  Y. 
Hind,  in  the  same.  Utah:  D.  B.  Huntley,  Tenth  Census,  Vol.  XIII., 
p.  463. 


THE  LESSER  METALS.  261 

bismuth  minerals,  and  not  a  few  other  places  in  the  country  con- 
tain traces,  but  the  San  Juan  is  the  only  serious  one  as  yet.1 

CHROMIUM. 

2.14.11.  Chromite,  whose  theoretical  composition  is  FeO.Cr2O3, 
with  Cr.2O3  68#,  often  has  MgO   and  Fe2O3  replacing  its  normal 
oxides.     The  percentage  of  O2O3  is  thus  reduced.    It  is  always 
found  in  association  with  serpentine,  which  has  resulted  from  the 
alteration  of  basic  rocks    consisting  of  olivine,  hornblende,    and 
pyroxene.     These  minerals  contain  the  chromic  oxide  probably  as 
a  base  in  their  fresh  condition,  but  lose  it  on  alteration.    A  chrome 
spinel,  picotite,  which  is  an  original  mineral  in  these  rocks,  likewise 
affords  it.    The  chromite  is  scattered  through  the  serpentine,  often 
forming  masses  of  large  size.     Traces  of  nickel  minerals  are   fre- 
quently noted  associated  with  the  chromite. 

2.14.12.  Example  49.     Disseminations  of  chromite  in  serpen- 
tine.    Pennsylvania  and  Maryland.     Great  areas  of  this  rock  are 
found  in  southeastern  Pennsylvania  and  in  the  adjacent  parts  of 
Delaware  and  Maryland.     Considerable  mining  has  been  done  in 
the  past.     \Voods  mine,  in  Lancaster  County,  Pennsylvania,  has 
furnished  great  quantities,  and  other  large  producers  are  situated 
in  the  Bare  Hills,  near  Baltimore.     This  section  is  now  no  longer 
commercially    productive.      Chromite   has    also   been    announced 
from  several  places  in  the  South,  no  one  of  which  has  yet  sent 
notable  quantities  to  the  market. 

2.14.13.  California.     As  already  mentioned  under  the  precious 
metals,  great  areas  of  serpentine  occur  on  the  western  flanks  of 
the  Sierras  and  in  the  Coast  range.     In  Del  Norte,  San  Luis  Obis- 
po,  Placer,  and  Shasta  counties,  California,  they  furnish  commer- 
cial amounts  of  chromite.     In  some  places  the  ore  is  followed  by 
underground  mining,  and  in  others  it  is  gathered  as  float  material. 
The  irregular  distribution,  always  characteristic  of  the  mineral, 
renders  underground  work  uncertain.    Good  ore  should  afford  50^ 
Cr2O3,  and   in    California    no   ore    less  than  47#  is  accepted.     It 
brings  in  the  East  $22  to  $35  per  ton.     Considerable  quantities 
are  imported.2 

1  Mineral  Resources  of  the  U.  £.,  1885,  p.  399.     B.  Silliman,  "  Bismuth- 
inite  from  the  Granite  District,  Utah,"  Amer.  Jour.  Sci.,  iii.,  VI.  123. 
H.  L.  Wells,  "  Bismuthosphaerite  from  Willimantic  and  Portland,  Conn  ," 
Amer.  Jour.  Sci.,  iii.,  XXXIV.  271. 

2  F.  D.  Chester,  Ann.  Rep.  Penn.  Survey,  1887,  p.  93,  describes  the 


2G2  KEMP'S  ORE  DEPOSITS. 

COBALT   (SEE  UNDER    "NICKEL"). 

MANGANESE. 

2.14.14.  Ores:  Pyrolusite  MnO2,  Mn.   63.2,   braunite,   Mn.2O3, 
Mn   69.68.     Some  SiO2,  which    may  be  chemically   combined,   is 
usually  present,  and  small  amounts  of  MgO,  CaO,  etc.     Psilome- 
lane  has  no  definite  composition,  but  usually  contains  barium  or 
other   impurities.     An    Arkansas    variety  has   afforded    Brackett 
MnO,  VV.85. 

There  are  various  other  oxides  and  hydroxides,  which  are  rare- 
ly abundant  enough  to  be  ores.  The  carbonate,  rhodochrosite, 
and  the  silicate,  rhodonite,  are  rather  common  gangue  minerals 
with  ores  of  the  precious  metals.  Franklinite  is  also  an  important 
source  (2.07.04).  Pyrolusite  and  psilomelane  are  the  commonest 
ores  the  country  over,  but  braunite  is  the  one  in  the  Batesville 
(Ark.)  region.  Manganese  is  widely  distributed,  and  yet  is  com- 
mercially important  in  but  few  localities.  It  imitates  limonite 
very  closely  in  its  occurrence  and  is  often  associated  with  this  ore 
of  iron.  To  make  a  manganese  ore  valuable,  at  least  40$  metallic 
manganese  should  be  present,  and  this  is  a  lower  limit  than  was 
formerly  admissible  when  the  ores  were  chiefly  used  in  chemical 
manufactures.  Under  present  conditions,  if  iron  is  present,  the 
ore  may  be  suited  to  spiegel,  although  even  lower  in  manganese 
than  401  Further,  there  should  be  low  phosphorus ;  Penrose 
says  not  over  0.2  to  0.25$  in  Arkansas,  and  not  over  12$  SiO2. 
High-grade  ores  run  50  to  60$  manganese. 

2.14.15.  Example  50.     Manganese    ores,    chiefly    psilomelane 


serpentine  along  the  State  line  near  Delaware.  D.  T.  Day,  Mineral  Re- 
sources of  the  U.  S.,  1882,  p.  428  ;  1883-84,  p.  567  (Rec.) ;  1885,  p.  357  ;  1886, 
p.  176 ;  1887,  p.  132.  J.  Eyerman,  "  On  Woods  Mine,  Pennsylvania,"  Min- 
eralogy of  Penn.j  Easton,  1889.  P.  Eraser,  "The  Northern  Serpentine 
Belt  in  Chester  County,  Pennsylvania,"  M.  E.,  XII.  349.  Rep.  C3  (Lan- 
caster County),  Penn.  Geol.  Survey.  T.  H.  Garrett,  "Chemical  Examina- 
tion of  Minerals  associated  with  Serpentine,"  Amer.  Jour.  Sci.,  ii.,  XIII. 
45,  and  XV.  332.  Also  F.  A.  Genth,  Amer.  Jour.  Sci.,  ii.,  XLI.  120.  E. 
Goldsmith,  "  Chromite  from  Monterey  County,  California,  "Phil.  Acad.Sci., 
1873,  p.  365.  William  Irelan,  Jr.,  Reps.  Cal.  State  Mineralogist,  especially 
1890,  pp.  167,  189,  313,  582,  583,  638.  G.  H.  Williams,  "The  Gabbros  and 
Associated  Hornblende  Rocks  near  Baltimore,"  Bull.  23,  U.  S.  Geol.  Sur- 
vey, pp.  50-59.  "  The  Geology  of  the  Crystalline  Rocks  near  Baltimore," 
distributed  at  the  Baltimore  meeting  of  the  Institute  of  Mining  Engineers, 
February,  1892.  Rec. 


THE  LESSER  METALS. 


263 


and  pyrolusite,  often  in  concretionary  masses,  disseminated  through 
residual  clay,  which  with  the  ores  has  formed  by  the  alteration  of 
limestones  and  shales.  The  deposits  are  entirely  analogous  to 
Examples  2  and  2«,  under  "  Iron."  Along  the  Appalachians 
the  favorite  horizon  is  just  over  the  Cambrian  (Potsdam)  quartzite. 
Such  is  the  case  at  Brandon  and  South  Wallingford,  Vt.,  where 
the  ores  occur  in  a  great  bed  of  clay  between  quartzite  and  lime- 
stone. They  are  referred  to  under  Example  2a,  where  mention  is 
made  of  the  associated  limonites  and  interesting  lignite.  They 
have  never  been  important  producers  of  manganese.  Crimora,  in 


•__*.•*  --^ 

SECTION    NO.  2. 


SECTION    NO.  4. 


FIG.  63. — Sections  of  the  Crimora  manganese  mine,  Virginia.     The  trough 

is  formed  by  Potsdam  sandstone  and  is  filled  with  clay  carrying 

nodules  of  ore.     After  C.  E.  Hall,  M.  E.,  June,  1891. 

Augusta  County,  Virginia,  is  the  largest  mine  in  the  country.  The 
containing  clay  bed  is  very  thick,  as  a  drill  hole  of  276  feet  failed 
to  strike  rock.  The  ores  occur  in  pockets,  which  as  a  maximum 
are  5  to  6  feet  thick  and  20  to  30  feet  long,  and  of  lenticular 
shape.  Other  irregular  stringers  and  smaller  masses  run  through 
the  clay,  which  preserves  the  structure  of  the  original  rock. 
Potsdam  quartzite  underlies  it.  Other  similar  bodies  occur  at 
Lyndhurst  and  elsewhere  in  the  Great  Valley  of  Virginia.  Less 
important  deposits  are  found  at  higher  horizons.  Cartersville, 
Ga.,  is  second  to  Crimora  in  production.  The  ores  again  occur  in 
pockets  in  a  stiff  clay  and  are  associated  with  quartzite,  which  is 
not  sharply  identified  as  yet.  It  may  be  Cambrian  (Potsdam)  or 
Tipper  Silurian  (Medina).  West  of  Cartersville  is  the  Cave  Spring 


IDEAL  SECTIONS  SHOWING  THE  FORMATION  or  MANGANESE-BEARING 
CLAY  FROM  THE  DECAY  OF  THE   ST.CLAIR  LIMESTONE. 

dBoONE   CHERT  MANGANESE-BEARlNfc  CLAY  rTllZARD  LIMESTONE 

EDSACCHAROIDAL  SANDSTONE 


ST.CLAIR  LIMESTONE; 


S*S«^F~J&''S-2§r 

^l^p^l-g^ 
Zgjjj&s&t* 

1        .      1             1             1             1 

i       i       i        i       i 

1        1        1        1    I    1    .    1  .  .,    1 

i       i        i       i 

i        i        i 

"~\  —  —  ]  —  —  1  —  —  1  —  —  1  —  —  1  —  —  1  — 

i       i        i        i 

i    '    i    '    i 

II                  1                1                 1                 1 

i       i       i        i       i 

i        i 

F          1          i           !          1           1          I 

i       i        i       i 

i        i        i 

Fia.  1.— ORIGINAL  CONDITION  OF  THE  ROCKS. 


1           1           I           I           L_ 

^^^^^^W 

^S^».        |                |                 | 

-f='—  P1" 

t           I 

1           1           1           1          1 

1^1                 1                1 

1                 1 

1            1           1 

1           1           1           II 

1                 1                I                1 

I                1 

1            1 

i                |                 1                1 

1                 1 

1            1           1 

1                      1                        1                      1                       1 

1                 1                1-                1 

1                1 

1            1 

1           II            II 

1               I                 1                1 

1            ! 

1            1           1 

:;'•-.•'•.'•'.  •••.  •:•."•.*.  •'.;-.  •'  •':/.•  .* 

FIG.  2.— FIRST  STAGE  OF  DECOMPOSITION. 


FIG.  3.— SECOND  STAGE  OF  DECOMPOSITION. 


FIG.  4.— THIRD  STAGE  OP  DECOMPOSITION. 


FIG.  64. — Geological  sections  illustrating  the  formation  of  the  manganese 
ores  in  Arkansas.     After  R.  A.  F.  Penrose,  Oeol.  Survey  of  Ark., 
1890,  Vol.  L,p.  177.  264 


THE  LESSER  METALS. 


265 


region,  where  the  ores  occur  with  Lower  Silurian  cherts.  There 
are  numerous  other  localities  not  yet  of  commercial  importance 
along  the  Appalachians,  in  Tennessee  and  elsewhere.  Full  de- 
scriptions will  be  found  in  Penrose's  report,  cited  below. 

2.14.16.     Batesville,  Ark.     The  ore  is  braunite,  and  is  found  in 
masses  disseminated  in  a  residual  clay  left  by  the  alteration  of  a 


FIG.  Q5.—The  Turner  mine,  Batesville  region,  Arkansas.    After  B,  A.  F. 
Penrose,  Geol.  Survey  Ark,,  1890,  Vol.  L,  p.  272. 

limestone  locally  called  the  St.  Clair.  It  is  of  geologic  age  be- 
tween the  Trenton  and  Niagara  periods,  and  is  underlain  by 
another  limestone  called  the  Izard,  which  is  later  than  the  Calcif- 
erous.  On  the  St.  Clair  a  series  of  cherts  called  the  Boone  cherts 
is  found,  which  is  of  Subcarboniferous  (Mississippian)  age.  The 
clays  are  sometimes  in  valleys,  sometimes  on  hillsides,  according 
to  the  unequal  decay  of  the  limestone.  South  of  the  Bates- 
ville district  are  the  Boston  Mountains,  a  range  of  low  hills  500 


266  KEMP'S   ORE  DEPOSITS. 

feet  high,  and  from  these  the  manganiferous  rocks  form  a  low 
monocline  to  the  north.  This  district  is  in  northern  central  Ar- 
kansas. Southwestern  Arkansas  contains  a  second  district  in 
which  the  ore  occurs  in  a  great  stratum  of  novaculite  of  probable 
Lower  Silurian  age.  The  ores  are  of  no  practical  importance, 
being  too  lean  and  too  disseminated.  Small  amounts  of  manga- 
nese ore  have  been  obtained  in  California,  in  San  Joaquin  County, 
and  from  Red  Rock,  in  San  Francisco  harbor.  The  former,  and 
perhaps  others  in  the  State,  may  prove  important  hereafter. 

2.14.17.  Quite  productive  deposits  are  found  in  pockets  at 
Markhamville,  Kings  County,  N.  B.,  in  Lower  Carboniferous  lime- 
stone. Some  thousands  of  tons  have  been  shipped.  Other  mines 
are  situated  at  Quaco  Head.  At  Tenny  Cape,  in  the  Bay  of  Mi- 
nas,  Nova  Scotia,  is  another  deposit  in  Lower  Carboniferous  lime- 
stone which  has  furnished  several  thousand  tons  of  ore.  Others 
less  important  occur  on  Cape  Breton. 

The  production  of  manganese  ores  in  the  United  States  seems 
to  be  falling  off.  In  1887  it  reached  its  maximum,  34,524  long 
tons.  In  1889  it  was  23,927  tons,  divided  as  follows  :  The  Vir- 
ginias, 14,616;  Arkansas,  2528;  Georgia,  5208;  other  States,  1575.1 


1  ''Manganese  Mines  near  Santiago,  Cuba,"  Engineering  and  Mining 
Journal,  Nov.  24,  1888,  p.  439.  H.  P.  Brumell,  "Notes  on  Manganese  in 
Canada,"  Amer.  GeoL,  August,  1892,  p.  80.  D.  T.  Day,  Mineral  Resources, 
1882,  p.  424;  1883-84,  p.  550.  F.  P.  Dunnington,  "On  the  Formation  of 
the  Deposits  of  Oxides  of  Manganese,"  Amer.  Jour.  Sci.,  iii.,  XXXVI.  175. 
Rec.  W.  M.  Fontaine,  "Crimora  Manganese  Deposits,"  The  Virginias, 
Mirch,  1883,  pp.  44-46.  Rec.  C.  E.  Hall,  "  Geological  Notes  on  the  Man- 
ganese Ore  Deposits  of  Crimora,  Va.,"  M.  E.,  June,  1891.  E.  Halse,  "Notes 
on  the  Occurrence  of  Manganese  Ore,  near  Mulege,  Baja  California,  Mex- 
ico," Trans.  N.  of  Eng.  Min.  and  Mech.  Eng.,  XLI.  302,  1892.  H.  Hoy, 
"Ores  of  Manganese  and  their  Uses,"  Proc.  and  Trans.  N.  S.  Inst.  Nat. 
Sci.,  Halifax,  II.,  1864-65,  p.  139.  "  Manganese  Mining  in  Merionethshire, 
England,"  Engineering  and  Mining  Journal,  Dec.  18,  1886,  p.  438.  R.  A. 
F.  Penrose,  Ann.  Rep.  Ark.  Geol.  Survey,  1890,  Vol.  I.  The  best  work 
published.  Rec.  "  Origin  of  the  Manganese  Ores  of  Northern  Arkansas," 
etc.,  A.  A.  A.  S.,  XXXIX.  250.  J.  D.  Weeks,  Mineral  Resources  of  the 
U.  S.,  1885,  p.  303  (Rec.) ;  1886,  p.  180;  1887,  p.  144.  D.  A.  Wells,  "On 
the  Distribution  of  Manganese,"  A.  A.  A.  S.,  VI.  275.  C.  L.  Whittle, 
"Genesis  of  the  Manganese  Deposits  at  Quaco,  N.  B.,"  Proc.  Bost.  Soc. 
Nat.  Hist,  XXV.,  p.  253. 


CHAPTER   XY. 

THE   LESSER   METALS,    CONTINUED— MERCURY,    NICKEL  AND 
COBALT,   PLATINUM,  TIN. 

MERCURY. 

2.15.01.  Ores  :  Cinnabar,  HgS.     Hg.  86.2,  S.   13.8.     Metacin- 
nabarite  is  a  black  sulphide  of  mercury.     Native    mercury  also 
occurs. 

Mercury  deposits  are  found  in  workable  quantities  in  the 
United  States  only  in  California,  in  Oregon,  and  in  one  locality 
in  Nevada.  ,  In  all  cases  cinnabar  is  the  principal  ore.  The  Cali- 
fornia deposits  are  limited  to  the  Coast  range  and  in  their  forma- 
tion seem  to  have  followed  great  basaltic  eruptions  of  post-Plio- 
cene age. 

2.15.02.  Example  50.     New   Alinaden.     Cinnabar   with    sub- 
ordinate native  mercury,  in  a  gangue  of  crystallized  and  chalce- 
donic  quartz,  calcite,  dolomite,  and  magnesite,  forming  a  stockwork, 
or   "chambered  vein,"  in  shattered  metamorphic  rocks    (pseudo- 
diabase,  pseudo-diorite,    serpentine,  and  sandstone).      There    are 
two  main  fissures,  making  a  sort  of  Y,  with  a  wedge  of  country 
rock  between.     The  ore  bodies  are  in  the  fissures  and  also  in  the 
intervening  wedge,  and  have  associated  with  them  much  attrition 
clay.     A  great  dike  of  rhyolite  runs  nearly  parallel  to  the  fissures, 
and  to  this   Becker  attributes  the   activity  of  circulations  which 
filled  the  vein.     New  Idria  is   farther  south,  high  up  toward  the 
summit   of  the  Coast  range.     The  ore  is  deposited  in  shattered 
metamorphic  rocks  of  Neocomian  (Lower  Cretaceous)  age,  and  in 
overlying  Chico  beds.     The  ore  is  accompanied  by  bitumen.     Ba- 
salt is  abundant  ten  miles  away.     North  of  San  Francisco  other 
mine£  have  been  opened,   among  which  are  the  Oat   Hill,  Great 
Eastern,  and  Great  Western.     The  mines  are  in  a  region  pierced 
by  eruptions  of  basalt  and  andesite,  which  doubtless  gave  impetus 


268 


KEMPS   ORE  DEPOSITS. 


to  the  ore-bearing  solutions.     The  ores  are  deposited  in  both  meta- 
morphic  and  unaltered  sedimentary  rocks. 

2.15.03.  Example  50a.  Sulphur  Bank.  This  is  in  the  same 
general  region  as  the  last,  but  from  its  peculiar  character  has  been 
one  of  the  best  known  of  ore  deposits.  A  great  flow  of  basalt  has 
come  down  to  the  shores  of  Clear  Lake  from  the  west.  Waters 
charged  with  alkaline  (including  ammonia)  carbonates,  chlorides, 
borates,  and  sulphides,  and  with  CO2,  H2S,  SO2,  and  marsh  gas, 
have  circulated  through  it.  Sulphur  and  sulphuric  acid  have 
formed  at  the  surface,  and  the  latter  has  dissolved  the  bases  of 
the  rock,  leaving  pure  white  silica  behind.  Lower  down,  cinnabar 


FIG.  66. — Section  of  the  Great  Western  cinnabar  mine.    After   G.  F. 
Becker,  Monograph  XIII. ,  U.  S.  Geol.  Survey,  p.  360. 

is  found,  both  in  the  basalt  and  in  the  underlying  sedimentary 
rocks,  with  other  sulphides  and  chalcedony.  Leconte  attributed 
its  precipitation  to  cold  surface  waters,  charged  with  sulphuric 
acid,  which  trickled  down  and  met  the  hot  alkaline  solutions. 
Becker  refers  the  same  -to  the  ammonia  set  free  toward  the  sur- 
face by  diminished  heat  and  pressure.  The  California  cinnabar 
deposits  have  been  often,  but  wrongly,  referred  to  vapors  of  the 
sulphide  volatilized  by  internal  heat  and  condensed  above. 

2.15.04.  Example  50&.  Steamboat  Springs,  Nevada.  These 
springs  are  in  Nevada,  only  six  miles  from  the  Comstock  Lode. 
Granite  is  the  principal  rock,  while  on  it  lie  metamorphic  rocks 
of  the  Jura-Trias,  and  much  andesite  and  basalt.  The  hot  springs, 
coming  up  through  small  fissures,  deposit  chalcedony  in  some 


THE  LESSER  METALS,   CONTINUED.  269 

places,  carDonates  in  others,  with  cinnabar  as  well  as  gold.  The 
following  minerals  have  been  noted  :  "  Sulphides  of  arsenic,  anti- 
mony, sulphides  or  sulphosalts  of  silver,  lead,  copper,  and  zinc,  ox- 
ide, and  possibly  sulphide  of  iron;  manganese,  nickel  and  cobalt 
•compounds,  and  a  variety  of  the  earthy  minerals  "  (Becker).  Becker 
thinks  the  source  of  the  cinnabar  is  in  all  classes  in  the  underlying 
granite,  and  that  it  has  come  up  in  solution  with  sodium  sulphide, 
and  been  precipitated  toward  the  surface  by  the  other  compounds 
in  the  hot  alkaline  waters,  with  which  it  would  remain  in  solution 
at  greater  depths,  temperatures,  and  pressures.  The  Steamboat 
Springs  are  often  and  properly  cited  as  metalliferous  veins  in  ac- 
tive process  of  formation.1 

INICKEL   AND  COBALT. 

2.15.05.  These   two    metals  almost   always    occur   together. 
Their  ores  are  the  following  : 

Millerite NiS,  Ni.  64.4  S.  35.6. 

Niccolite NiAs,          Ni.  44.0  As.  56.0. 

Linnaeite Co3S4          Co.  58.0  S.  42.0. 

Also  in  small  percentages  in  pyrrhotite,  and  a  few  oxidized  com- 
pounds. They  may  be  in-  pyrrhotite  as  the  doubtful  mineral 
polydymite,  a  sulphide  of  Co,  Ni,  and  Fe. 

2.15.06.  Example  16c.      (See  2.03.16  and  2.04.02.)     Pyrrhotite 
Beds   or  Veins.     Lenticular  masses  of  pyrrhotite   interbedded  in 

1  W.  P.  Blake,  "  Quicksilver  Mine  at  Almaden,  Cal.,"  Amer.  Jour. 
Sci.,  ii,  XVII.  438.  G.  F.  Becker,  "Quicksilver  Deposits  of  the  Pacific 
Slope,"  Monograph  XIII. ,  U.  S.  Geol.  Survey,  Chap.  17.  Rec.  "  On  New 
Almaden,''  Cal.  Geol.  Survey,  I.,  p.  68.  S.  D.  Christv}  "  On  the  Genesis 
of  Cinnabar  Deposits,"  Amer.  Jour.  Sci.,  June,  187^j).'453  ;  Engineering 
and  Mining  Journal,  Aug.  2,  1879,  p.  65.  D.  de  Cortazar,  "General  Re- 
view of  Occurrence,  etc.,  of  Mercury,"  Reps,  and  Awards  Group  I.,  Cen- 
tennial Exposition,  p.  196.  William  Irelan,  Ann.  Reps.  Cal.  State  Mineral- 
ogist. Laur,  "On  Steamboat  Springs,"  Annales  des  Mines,  1863,  423. 
J.  Leconte  and  Rising,  "Metalliferous  Vein  Formation  at  Sulphur  Bank," 
Amer.  Jour.  Sci.,  July,  1882 ;  Engineering  and  Mining  Journal,  Aug.  26, 
1882,  p.  109.  J.  Leconte,  "On  Steamboat  Springs,"  Amer.  Jour.  Sci., 
June,  1883,  p.  424.  -  "Genesis  of  Metalliferous  Veins,"  Amer.  Jour.  Sci., 
July,  1883.  J.  A.  Phillips,  "On  Sulphur  Bank,  California,"  Phil.  Mag., 
1871,  p.  401 ;  Quar.  Jour.  Geol.  Sci.,  XXXV.,  1879,  p.  390.  Rolland,  An- 
nales des  Mines,  XIV.,  384,  1878.  B.  Silliman,  "  Notes  on  the  New  Al- 
maden Quicksilver  Mines,"  Amer.  Jour.  Sci.,  ii.,  XXXVII.  190.  Siveking, 
B.  und  H.  Zeitung,  1876,  p.  45. 


270  KEMP'S   ORE  DEPOSITS. 

gneisses  and  schists  as  described  for  pyrite.  They  are  known  at 
various  places  in  the  East.  Openings  have  been  made  at  Lowell, 
Mass.,  Chatham  and  Torrington,  Conn.,  and  Anthony's  Nose, 
N.  Y.,  the  last  in  search  of  pyrite  for  sulphuric  acid.  Nickel  ap- 
pears up  to  3#  of  the  ore,  but  these  mines  have  never  amounted  to 
much.1 

2.15.07.  Example   IQd.     Gap  Mine,  Lancaster  County,  Penn- 
sylvania.    A  great  wedge  or  lense  of  hornblende  rock  appears  to 
be  inclosed  in  mica  schists.     For  a  space  of  from  6  to  30  feet  of 
its  outer  portion  it   is  impregnated  with  millerite,  chalcopyrite, 
siderite,  etc.     The  millerite   occurs   as   a   coating,   lining  cracks. 
Nickeliferous  pyrrhotite  is  also  found.     A  great  trap  dike  is  near. 
The  mine  is  not  at  present  worked.     It   presents   some  important 
analogies  with  the  Sudbury  deposits.2 

2.15.08.  Example  16c.    Sudbury  District,  Ontario.     Breccia  of 
diorit.e,  cemented  by  nickeliferous  pyrrhotite  and  chalcopyrite,  form- 
ing large  but  more  or  less  irregular  deposits;  also  deposits  of  purer 
sulphides,  apparently  in  great  veins.     An  extensive  area  of  Huro- 
nian  schistose  rocks  runs  northwesterly  from  the  juncture  of  Lakes 
Superior  and  Huron.     It  contains  some  Archaean  inliers,  and  two 
great  belts  of  diorite  whose  strike  is  northeast,  parallel  with  the 
schists.     These  latter  include  a  great  variety  of  rocks  and  dip  at 
a  high  angle.     The  diorites  are  crossed  in  places  by  diabase  dikes, 
which  seem  to  exert  an  enriching  influence.     Also,  where  the  dio- 
rite belt  pinches  in,  ore  bodies  are  found  near  gneiss  and  quartz 
syenite.     Where  the  breccia  structure  is  developed  they  clearly  lie 
in  lines  of  dynamic  disturbances  which  are  parallel  with  the  gen- 
eral strike.     The  purer  deposits,  as  in  the  Stobie  mine,  present  a 
great  thickness  of  pyrrhotite.     In  the  instance  cited  it  is  160  feet 
across;  but  even  in  this,  horses  of  diorite  and  more  or  less  angular 
inclusions  occur.     The  chalcopyrite  is  in   pockety  masses  in  the 
pyrrhotite.     The  deposits  extend  seventy  miles  in  a  northwest  di- 
rection, and   over  a  maximum  breadth  of  fifty  miles.     They  pro- 
duce far  more  nickel  than  any  other  region.    The  interesting  plati- 

1  H.  Credner,  "Anthony's  Nose,"  B.  und  H.  Zeit.,  1866,  p.  17.     W.  E. 
C.  Eustis,  "The  Nickel  Ores  of  Orford,  Quebec,"  M.  E.,  VI.  208.     Engi- 
neering and  Mining  Journal,  March  16,  1878.  • 

2  W.  P.  Blake,  Mineral  Resources,  1882,  p.  399.     J.  Eyerman,  Miner- 
alogy  of  Penn.     P.  Fraser,  Rep.  CCC,  Second  Penn.  Survey,  p.  163.    Whar- 
ton,  "Analyses  of  Nickel  Ore  from  the  Gap  Mine,"  Phil.  Acad.  Sci.,  1870, 
p.  6. 


THE  LESSER  METALS,    CONTINUED.  271 

num.  compound,  sperrylite,  from  this  region,  is  mentioned  under 
"  Platinum."  l 

2.15.09.  Example  23a.     Mine  la  Motte.     Considerable  pyrite 
occurs  with  the  lead  ores  mentioned  under  Example  23,  and  this  is 
separated  in  the  ore  dressing  and  treated  by  itself,  as  it  contains 
nickel  and  cobalt.    Such  pyrite  is  most  abundant  at  Mine  la  Motte, 
and  considerable  matte  is  made  and  shipped  abroad.    The  siegenite 
in  Potsdam  sandstone  is  interesting,  but  not  abundant  enough  to- 
be  practically  available.     See  under  Example   23  for  additional 
literature.2 

2.15.10.  Numerous  other  localities  of  nickel  ores,  chiefly  of 
oxidized  character,   have  been  reported,  as  at  Webster,  Jackson 
County,  N.  C.,  in  the  olivine  rock,  dunite  ;  in  Nevada  at  the  Love- 
lock mines,  Churchill  County,  and  near  Riddle  Station,  Douglass; 
County,  Ore.     At  the  last  place  the  ores  are  hydrated  silicates  of 
magnesium  and  nickel  associated  with  serpentine,  which  is  derived 
from  an  altered  olivine  rock.     Nickeliferous  pyrrhotite  is  reported 
in  the  neighboring  county,  Jackson,  at  Rock  Point.     Nickel  ores 
have  also  been  reported  from  Salina  County,  Arkansas.     Millerite 
occurs  in  a  vein  with  quartz  gangue  in  black  shales.     It  is  not 
practically  productive.     Nickel  is  also  reported  in  a  rather  fine 
conglomerate  from  Logan  County,  Kansas.     It  occurs  with  man- 
ganese and  limonite  in  the  cementing  material  of  the  rock. 

In  1887  there  were  produced  183,125  Ibs.  of  metallic  nickel  in 
the  United  States,  and  144,841  Ibs.  in  1891.  Canada  produced 
1,336,627  Ibs.  in  1891.3 

2.15.11.  The  principal   foreign  source  of  nickel  is  New  Cale- 

1  A.  E.  Barlow,  "On  Sudbury,"  Ottawa  Naturalist,  June,  1891.     R. 
Bell,  "  The  Nickel  and  Copper  Deposits  of  the  Sudbury  District,  Canada," 
Butt.  Geol.  Soc.  Amer.,  Vol.  II.,  p.  125.     T.  G.  Bonney,  "Notes  on  a  Part 
of  the  Huronian  Series  near  Sudbury,  Canada,"  Quar.  Jour.  Geol.  Sci., 
XL1V.  32.     F.  W.  Clarke  and  Ch.  A.  Catlett,  "  Platiniferous  Nickel  Ore 
from  Canada,"  Amer.  Jour.  Sci. ,  iii.,  XXXVII.  372.     J.  H.  Collins,  "  Notes 
on  the  Sudbury  Ore  Deposits,"  M.  E.,  October,  1889,  Engineering  and 
Mining  Journal,  Oct.  26,  1890  ;  B.  und  H.  Zeit.,  Vol.  L.,  p.  148.     E.  D. 
Peters,  "  On  Sudbury  Ore  Deposits,"  M.  E.,  October,  1889 ;  Engineering 
and  Mining  Journal,  Oct.  26,  1890 ;  B.  und  H.  Zeit.,  Vol.  L.,  p.  148. 

2  J.  M.  Neill,  "Notes  on  the  Treatment  of  Nickel  and  Cobalt  Mattes- 
at  Mine  la  Motte,"  M.  E.,  XIII.  634. 

3  Ark.  Geol.  Survey,  1888,  Vol.  L,  pp.  34,  35.     F.  P.  Dewey,  "On  the 
Nickel  Ores  of  Russell  Springs,  Logan  County,  Kansas,"  M.  E.,  XVII. 
S.  H.  Emmons,  "The  Nickel  Deposits  of  North  Carolina,"  Engineering' 
and  Mining  Journal,  April  30,  1892.     H.  B.  v.  Foullon,  "On  Riddle,. Ore- 


272  KEMP'S   ORE  DEPOSITS. 

<lonia,  in  the  South  Pacific.  The  ores  are  garnierite  and  other 
hydrated  silicates  of  nickel  and  magnesium  in  serpentine.  In  1890 
they  furnished  885,300  Ibs.  Norway  conies  next,  and  in  1889  pro- 
duced 149,872  Ibs.  Sweden  in  the  same  year  afforded  17,632  Ibs. 
These  latter  are  from  sulphide  ores.1 

PLATINUM. 

2.15.12.  Some  hundreds  of  ounces  of  platinum  are  annually 
gathered  from  placer  washings  in  northern  California,  and  two  or 
three  times  as  much  more  from  British  Columbia.  Much  iridium 
and  osmium  are  associated  with  it.  In  October,  1889,  F.  L.  Sperry, 
the  chemist  of  the  Canadian  Copper  Company,  of  Sudbury,  dis- 
covered a  heavy  crystalline  powder  in  the  concentrates  of  a  small 
gold-quartz  mine  in  the  district  of  Algoma.  He  detected  the 
presence  of  platinum,  and  sent  the  material  to  Professors  Wells 
and  Penfield  of  Yale,  by  whom  it  was  analyzed,  and  crystallo- 
graphically  determined  to  be  the  arsenide  of  platinum,  PtAs2,  the 
first  compound  of  platinum,  other  than  an  alloy,  detected  in 
nature.  It  has  been  appropriately  named  sperrylite  by  Wells,  and 
although  not  at  present  a  source  of  platinum,  it  may  merit  atten- 
tion, as  the  price  of  the  metal  has  recently  approximated  that  of 
gold.  The  chief  reliance  of  the  world  for  platinum  is  Russia, 
whose  deposits  are  in  the  Urals.  More  or  less  comes  also  from 
Colombia,  South  America,  and  from  placer  washings  elsewhere. 
Serpentine  is  very  generally  its  mother-rock.2 

gon,"  Jahrbuch  d.  k.  k.  geol.  Reichsanstalt,  Vienna,  XLIL,  223,  1892. 
Rec.  A.  D.  Hodges,  "Notes  on  the  Occurrence  of  Nickel  and  Cobalt  in 
Nevada,"  M.  E.,  X.  657.  W.  R.  Ingalls,  General  paper,  Engineering  and 
Mining  Journal,  Jan.  2,  1892,  p.  40.  Rec.  Mineral  Resources,  1887,  p. 
126.  S.  B.  Newberry,  "Nickel  Ores  from  Nevada,"  Amer.  Jour.  Sci.,  iii., 
II.  122.  H.  Wurtz,  "On  the  Occurrence  of  Cobalt  and  Nickel  in  Oaston 
County,  North  Carolina,"  Amer.  Jour.  Sci.,  ii.,  XXVII.  34. 

1  J.  Heard,  Jr.,   "Caledonia  Nickel  and  Cobalt,"  Engineering  and 
Mining  Journal,  Aug.  11,  1888,  p.  103.    J.  H.  L.  Vogt,  "On  Nickel  Pro- 
duction and  Occurrence."    Good  paper  in  Swedish  :  Geologiska  Forenin- 
gens,  i.  Stockholm,  Band,  XIV.,  p.  433. 

2  California :  Engineering  and  Mining  Journal,  June  29,  1889,  587. 
B.  Silliman,  "Cherokee  Gold  Washings,  California,"  Amer.  Jour.  Sci., 
iii.,  VI.  132.      Canada:  F.  W.  Clarke  and  Ch.  Catlett,   " Platiniferous 
Nickel  Ore  from  Canada,"  Amer.  Jour.  Sci.,  iii.,  XXXVII.  372.     H.  L. 
Wells  and  S.  L.  Penfield,  "Sperrylite,  a  New  Mineral,"  Amer.  Jour.  Sci., 
iii.,  XXXVII.  67.     Russia:  A.  Daubree,  "On  the  Platiniferous  Rocks  of 
the  Urals,"  Trans.  French  Acad.  Sci.,  March,  1875  ;  Amer.  Jour.  Sci.,  iii., 
IX.  470.     General  paper  by  C.  Bullraan,  The  Mineral  Industry  for  1892, 

>.  373.     Rec. 


THE  LESSER  METALS,    CONTINUED.  273 

TIN. 

2.15.13.  Ores  :  Cassiterite,  SnO2,  Sn.  78.67,  O.  21.33.  The  sul- 
phide stannite  is  a  rather  rare  mineral. 

Cassiterite  occurs  in  small  stringers  and  veins  on  the  borders 
of  granite  knobs  or  bosses,  either  in  the  granite  itself  or  in  the 
adjacent  rocks,  in  such  relations  that  it  is  doubtless  the  result  of 
fumarole  action  consequent  on  the  intrusion  of  the  granite.  It 
appears  that  the  tin  oxide  has  probably  been  formed  from  the 
fluoride.  A  favorite  rock  for  the  ore  is  the  so-called  greisen,  a 
mixture  of  quartz  and  muscovite  or  lithia  mica,  and  probably  an 


FIG.  67.—  Horizontal  section  of  the  Etta  knob.     After  W.  P.  Blake,  Min- 
eral Resources,  1884,  p.  602. 

original  granite  altered  by  fumarole  action.  Topaz,  tourmaline, 
and  fluorite  are  found  with  the  Cassiterite,  indicating  fluoric  and 
boracic  fumaroles.  Cassiterite  seems  also  to  crystallize  out  of  a 
granite  magma  with  the  other  component  minerals.  Cassiterite, 
being  a  very  heavy  mineral,  accumulates  in  stream  gravels,  like 
placer  gold,  affording  thus  the  stream  tin.  When  of  concentric 
character  it  is  called  wood  tin.  It  is  not  yet  demonstrated  that 
the  United  States  have  workable  tin  mines. 

2.15.14.  Example  51.  Black  Hills.  Knobs  of  granite  rock 
containing  cassiterite,  disseminated  in  a  mass  of  albite  and  mica, 
and  associated  with  immense  crystals  of  spodumene.  Columbite, 
tantalite,  and  beryl  are  also  found.  There  are  two  granite  knobs 
which  are  best  known,  the  Etta  and  the  Ingersoll.  The  former  is  a 
conical  hill,  250  feet  high  by  150  feet  by  200  feet,  piercing  mica  and 
garnetiferous  slates.  Tunnels  show  it  to  have  a  concentric  struct- 
ure— first,  a  zone  of  mica  ;  second,  a  zone  of  great  spodumene 
crystals,  with  an  albitic,  so-called  greisen  and  cassiterite  in  the 


274  KEMPS  ORE  DEPOSITS. 

interstices  ;  lastly,  a  mixture  of  quartz  and  feldspar  as  a  core. 
Other  tin-bearing  granites  occur  as  dikes,  or  veins,  as  much  as  80 
feet  wide,  and  bearing  the  so-called  greisen  and  tin  ore  in  quartz. 
They  are  called  segregated  veins  by  Carpenter,  who  doubts  their 
igneous  character,  probably  on  good  ground.  No  tin  is  yet  com- 
mercially produced.  The  tin  deposits  extend  also  into  Wyoming.1 

2.15.15.  Tin  ores  as  stream  tin  have  been  found  in  gold  wash- 
ings in  Montana  and  Idaho.     Tin  is  also  known  in  the  Temescal 
Mountains,   southern    California,    and    according   to    Blake    is  in 
various  small  veinlets  in  a  granite  region.     This  locality  attracted 
much  interest  years  ago,  but  has  never  yielded  any  practical  re- 
sults until  lately.     Operations  after  being  carried  on  for  a  time 
have,  however,  proved  a  failure.2 

2.15.16.  Narrow  veins  carrying  cassiterite  are  being  exploited 
in   the   granite    and    schistose   rocks  of  Rockbridge   and   Nelson 
counties,  Virginia,  in  North  Carolina,  and  in  Alabama.     Compa- 
nies have  been  formed  to  work  the  two  former,  but  as  yet  without 
a  notable  output.3  w 

2.15.17.  Cassiterite  has  been  discovered  in  narrow  veins  in  mica 
schists  with  lepidolite  and  fluorite  at  Winslow,  Me.,  and  is  known 
at  other  places  in  Maine  and  New  Hampshire.     A  salted  tin  pros- 
pect several  years  ago  spread  the  impression  that  tin  was  to  be 
found  in  southwest  Missouri.* 

1  W.  P.  Blake,  Mineral  Resources,  1884-85,  p.  602.     Rec.    Amer.  Jour. 
Sci.,  September,  1883,  p.  235 ;  Engineering  and  Mining  Journal,  Sept.  8, 
1886.     "Tin  Ore  Deposits  of  the  Black  Hills,"  M.  E.,  XIII.  691.     F.  R. 
Carpenter,  Prelim.  Rep.  Dak.  School  of  Mines,  1888  ;  also  711.  E.,  XVII. 
570.     "Tin  in  the  Black  Hills,"  Engineering  and  Mining  Journal,  Nov. 
28,  1884,  p.  353.     Mineral  Resources  of  the  U.  S.,  annually  under  "  Tin.'' 

2  W.  P.  Blake,  "Occurrence  of  Wood  Tin  in  California,  Idaho,  and 
Montana,"  Mining  and  Scientific  Press,  San  Francisco,  Aug.  5,  1882.    H. 
G.  Hanks,  Rep.  Cal.  State  Mineralogist,  1884,  p.  121. 

3  H.  D.  Campbell,  "  Tin  Ore,  Cassiterite,  in  the  Blue  Ridge  in  Vir- 
ginia," The  Virginias,  October,  1883.     A.  R.  Ledoux,  "  Tin  in  North  Caro- 
lina," Engineering  and  Mining  Journal,  Dec.  14,  1889,  p.  521  ;  see  also 
February,  1887,  p.  111.     McCreath  and  Platt,  Bull.  Iron  and  Steel  Asso., 
Nov.  7,  1883,  p.  209.     W.  Robertson,  London  Mining  Journal,  Oct.  18, 1884. 
A.  Winslow,  "Tin  Ore  in  Virginia,"  Engineering  and  Mining  Journal, 
November,  1885.     Rec. 

4  W.  P.  Blake,  Mineral  Resources,  1884,  p.   538.     C.  H.  Hitchcock, 
"Discovery  of  Tin  Ore  and  Emery  at  Winslow,  Me.,"  Engineering  and 
Mining  Journal,  Oct.  2,  1880,  p.  218.     T.  S.  Hunt,  "  Remarks  on  the  Oc- 
currence of  Tin  Ore  at  Winslow,  Me.,"  M.  E.,  I.  573.     C.  T.  Jackson,  "  Tin 
Ore  tit  Winslow,  Me.,"  Proc.  Bost.  Soc.  Ndt.  Hist.,  XII.  267. 


CHAPTER  XYI. 

CONCLUDING  REMARKS. 

2.16.01.  In  review  of  the  western  border  of  the  country,  we 
note  the  elevated  plateau  rising  from  the  Mississippi  to  the  Rocky 
Mountain  range,  which  consists  of  various  ranges  of  general  north 
and  south  or  northwest  and  southeast  trend,  with  broad  valleys 
between.  Next  comes  the  Colorado  Plateau,  and  then  the  Wa- 
satch  Mountains  and  the  Great  Basin,  with  its  various  subordinate 
north  and  south  ranges.  *These  are  succeeded  by  the  Sierra  Ne- 
vada, and  the  great  valley  of  California,  the  Coast  range,  and 
finally  the  Pacific  Ocean. 

From  the  Archaean  to  the  close  of  the  Carboniferous  there 
were  granite  islands  around  which  active  sedimentation  proceeded. 
At  the  close  of  the  Carboniferous  the  elevation  of  the  Wasatch 
and  the  region  of  eastern  Nevada  occurred.  At  the  close  of  the 
Jurassic  the  elevation  of  the  Sierra  Nevada  took  place.  The  chief 
upheaval  of  the  Rocky  Mountain  system  came  at  the  close  of  the 
Cretaceous  and  that  of  the  Coast  range  at  the  close  of  the  Miocene 
Tertiary.  Smaller  and  less  important  oscillations  have  occurred 
before  and  since.  Each  elevation  was  accompanied  by  foldings, 
faultings,  and  extensive  outpourings  of  eruptive  rocks.  The  re- 
sultant fractures  and  the  solfataric  action,  occasioned  by  the 
dying  volcanic  activity,  constitute  the  primary  cause  of  the  for- 
mation of  the  ore  deposits,  which  in  some  cases  lie  in  ranges  along 
the  lines  of  faulting  or  of  disturbances,  and  in  others  are  irreg- 
ularly scattered.  We  can  recognize  the  Coast  range  belt  with 
mercury  and  chromium  ;  the  California  gold  belt  in  the  western 
Sierras;  the  silver  belt  of  Utah  on  the  western  flank  of  the  Wa- 
satch ;  a  belt  in  Arizona  from  southeast  to  northwest,  along  the 
contact  between  Paleozoic  limestone,  mostly  Carboniferous,  and 
the  Archaean  ;  and  the  great  stretch  of  lead-silver  mines  in  the 
Carboniferous  limestones  of  Colorado.  The  other  areas  are  scat- 


276  KEMP'S   ORE  DEPOSITS. 

tered,  and  apparently  exhibit  no  such  grand  general  relations  to 
these  geographical  and  geological  phenomena.1 

2.16.02.  In  the  Mississippi  Valley,  W.  P.  Jenney  has  re- 
marked the  connection  of  the  antimony  and  silver  deposits  of  Ar- 
kansas with  the  Ouachita  uplift  that  traverses  that  State  and  In- 
dian Territory  ;  also,  the  location  of  the  Missouri  lead  and  zinc 
ores  along  the  Ozark  uplift;  and  he  has  referred  the  Wisconsin 
lead  and  zinc  mines,  as  well  as  those  in  the  neighboring  part  of 
Iowa  and  Illinois,  to  an  uplift  south  of  the  Archaean  area  of  Wis- 
consin. The  limitation  of  the  Lake  Superior  copper  deposits  to  the 
Keweenawan  system  may  be  mentioned,  and  such  parallelism  as 
prevails  among  the  Lake  Superior  iron  ores.  In  the  East  the  great 
belt  of  Clinton  Ores  ;  the  long  succession  of  Siluro-Cambrian  limo- 
nites  in  the  Great  Valley  ;  the  black-band  ores  and  clayironstones- 
of  the  Carboniferous  ;  the  closely  similar  geological  relations  of 
nontitaniferous,  magnetite  lenses  in  the  Archaean  gneisses;  and 
the  general  association  of  titaniferous  magnetites  with  rocks  of  the 
gabbro  family  the  country  over — all  are  striking  illustrations  of 
broad,  general  geological  features  that  may  characterize  extended 
areas.  To  these  may  be  appended  the  great  series  of  pyritous 
beds  or  veins  in  the  slates  and  schists  of  the  East,  the  gold  belt  of 
the  southeastern  States,  and  the  small  copper  deposits  associated 
with  the  Triassic  traps  and  sandstones.  Aside  from  these,  while 
there  are  important  mines  not  included  in  the  list,  the  others  do 
not  exhibit  the  same  widespread  uniformities  of  structure  or  asso- 
ciations. Yet,  from  the  list  cited,  it  forcibly  appears  that  similar 
conditions  have  brought  about  related  ore  bodies  over  great 
stretches  of  country  ;  and  while  in  the  opening  schemes  of  clas- 
sification points  of  difference  were  emphasized,  in  the  closing  pages 
points  of  resemblance  may  be  with  equal  right  brought  to  the  fore- 
ground. 

2.16.03.     A  few  general  conclusions  suggest  themselves  from 
the  preceding  pages. 

(1)  The  extreme  irregularity  in  the  shape  of  metalliferous  de- 


1  G.  F.  Becker,  Amer.  Jour.  Sci.,  3d  Series,  Vol.  XXIII.,  1884  p.  209. 
W.  P.  Blake,  Rep.  Cal  State  Board  of  Agriculture,  1866.  S.  F.  Emmons, 
"  The  Structural  Relations  of  Ore  Deposits,"  M>  E.,  XVI.  804.  R.  W.  Ray- 
mond, "Geographical  Distribution  of  Mining  Districts  in  the  United 
States,"  M.  E.,  I.  33.  Fortieth  Parallel  Survey,  Vol.  III.,  Chap.  I.  "  Pre- 
cious Metals,"  Tenth  Census,  Vol.  XII. 


CONCLUDING  REMARKS.  277 

posits,  and  from  this  the  unwisdom  of  the  United  States  law  in 
the  West,  which  is  based  on  well-defined  fissure  veins.  The  only 
practicable  method  is  that  a  man  should  own  all  that  is  embraced 
in  his  property  lines,  whether  the  ore  body  outcrops  outside  or  not. 
"  A  square  location  is  the  square  thing  "  (Raymond). 

(2)  The  very  general  proximity  of  eruptive  rocks  in  some  form 
to  the  ore  bodies.     Except  in  the  case  of  iron,  there  are  only  a 
few  where  these  are  not  present,  and  apparently  strong  factors  in 
the  circulations  which  formed  the  ore.    The  lead  and  zinc  deposits 
of  eastern  and  western  Missouri  and  the  neighboring  States,  and 
of  Xew  York  and  Virginia,  are  almost  the  only  ones,  and  we  are 
justified  in  concluding  that  eruptive  rocks  are  of  great  importance. 

(3)  We  know  from  the  investigations  of  Sandberger  and  others 
that  the  dark  silicates  of  many  rocks  contain  percentages  of  the 
common  metals.     The  choice  is  open  whether  to  refer  the  ore  to 
original  dissemination  in  these,  and  derive  it  by  gradual  concentra- 
tion, probably  at  great  depths,   or  to  some  indefinite  unknown 
source,  which  can  only  be  described  as  "  below." 


ADDENDA. 

Page  65.  In  the  report  of  the  State  Geologist  of  Michigan  for 
1891-92  (issued  January,  1893),  pp.  144,  145,  Dr.  M.  E.  Wadsworth 
has  published  a  "  Preliminary  Classification  of  Metalliferous  or 
Ore  Deposits."  The  main  outline  is  as  follows  : 

I.    Eruptive   Deposits    (a)  Non-Fragmental. 

(b)  Fragmental. 
II.    Mechanical  Deposits  (a)  Unconsolidated. 

(b)  Consolidated. 
III.    Chemical    Deposits   (a)  Sublimations. 

(b)  Water  Deposits. 

(c)  Impregnations  or  Replacements. 

(d)  Segregations  or  Cavity  Deposits. 

Each  of  the  above  except  III.  (d)  is  then  subdivided  so  that 
the  table  becomes  practically  a  classification  of  rocks.  Indeed,  a 
moment's  consideration  will  show  that  the  scheme  in  its  main  divis- 
ions is  closely  modeled  after  the  prevailing  classification  of  rocks. 
III.  (d)  Segregations  or  Cavity  Deposits  contains  the  following  : 
1.  Pockets.  2.  Chambers.  3.  Contact  Deposits.  4.  Veins,  in- 
cluding Gash  Veins,  Segregated  Veins,  Reticulated  Veins  or  Stock- 
work,  Contact  Veins,  Fissure  or  Fault  Veins. 

The  author  states  in  some  appended  comments  that  the  table 
is  not  limited  to  those  deposits  now  practically  worked  (which  we 
ordinarily  understand  the  expression  ore  deposits  to  mean),  but  is 
intended  to  include  all  that  have  been  or  may  be  of  value.  But  in 
this  respect  there  is  good  ground  for  preferring  to  make  our  clas- 
sifications in  ore  deposits,  as  in  mineralogy,  zoology,  etc.,  embrace 
only  the  authenticated  varieties,  expecting  additions  to  be  incor- 
porated as  discovered  and  suitably  described. 

Page  73.  In  connection  with  the  precipitation  of  iron  ores  by 
limestones,  an  added  note  on  the  chemistry  of  the  reaction  is.desira- 
ble.  Dr.  J.  P.  Kimball,  in  a  paper  on  the  "  Genesis  of  Iron  Ores 
by  Isomorphous  and  Pseudomorphous  Replacement  of  Limestone," 


280  KEMP'S   ORE  DEPOSITS. 

etc.,  Amer.  Jour.  Sci.,  September,  1891,  p.  231  (the  paper  is  con- 
cluded in  the  American  Geologist,  December,  1891),  brings  out 
the  fact  that  alkaline  carbonates,  of  which  calcium  carbonate  is  one, 
precipitate  from  solutions  of  ferrous  sulphate  or  ferrous  carbonate, 
under  ordinary  conditions,  hydrous  ferrous  carbonate,  an  unstable 
salt  that  quickly  oxidizes  to  a  hydrous  oxide.  The  argument  is  then 
adduced  that  bodies  of  siderite  or  anhydrous  ferrous  carbonate 
could  not  have  originated  by  direct  precipitation,  but  have  prob- 
ably done  so  by  pseudomorphous  replacement  of  calcium  carbonate. 
The  author  then  follows  the  possible  metamorphism  or  changes  of 
these  bodies  to  other  forms  of  iron  ore,  citing,  however,  some  as 
possible  examples  that  are  clearly  unwarranted.  The  chemical 
distinctions  thus  brought  out  undoubtedly  have  their  weight  and 
importance  ;  but  siderite  as  a  frequent  veinstone  crystallizes  as  the 
anhydrous  carbonate,  and  in  surroundings  giving  no  reason  to  in- 
fer that  it  has  replaced  calcium  carbonate.  It  has  also  been  ob- 
tained artificially  by  several  investigators  (as  cited  by  Fouque  and 
Levy  in  Synthese  des  Mineraux  et  des  Roches),  and  there  is  still 
reason  for  believing  that  it  does  not  necessarily  always  form  in 
nature  as  a  pseudomorph  after  calcium  carbonate. 

Page  74.  Attention  has  been  lately  directed  to  the  great  de- 
posits of  bog  ore  in  the  Three  Rivers  district  of  Quebec.  (P.  H. 
Griffin,  "  The  Manufacture  of  Charcoal-Iron  from  the  Bog  and  Lake 
Ores  of  Three  Rivers  District,  Province  of  Quebec,  Canada,"  Trans. 
Inst.  Min.  Eng.,  Montreal  meeting,  February,  1893.)  Although  the 
deposits  have  been  long  known  and  have  been  the  basis  of  a  small 
industry,  they  are  now  utilized  on  a  larger  scale  for  car-wheel  iron. 
They  occur  in  the  small  lakes  and  swamps  that  receive  the  drain- 
age of  the  old  Laurentian  highlands  on  the  north.  This  water, 
more  or  less  charged  with  iron,  drops  its  burden  as  bog  ore  wher- 
ever it  stands.  By  collecting  supplies  from  a  fairly  extended  dis- 
trict, quite  large  amounts  of  ore  are  obtained.  The  deposits  fur- 
nish ideal  illustrations  of  the  general  origin  of  bog  ores,  as  outlined 
in  preceding  pages.  They  occur  also  on  the  bottoms  of  lakes  and 
are  obtained  by  dredging.  The  lake  ore  seems  to  run  somewhat 
richer  than  that  gathered  in  the  bogs.  Both  are  low  in  sulphur 
but  have  about  0.3$  phosphorus. 

Page  78.  Volume  I.  of  the  Annual  Report  of  the  Geological 
Survey  of  Arkansas  consists  of  a  report  by  R.  A.  F.  Penrose  on 
the  "  Iron  Deposits  of  Arkansas."  It  at  once  appears  that  there  is 
little  prospect  of  Arkansas  producing  any  notable  amounts  of  iron 


ADDENDA.  281 

ore.  Such  as  have  been  found  are  practically  all  limonite  or  brown 
hematite,  and  are  generally  very  low  in  iron.  The  ores  occur  in 
five  districts,  viz.:  Northeastern  Arkansas,  northwestern  Arkansas, 
the  valley  of  the  Arkansas  River,  the  Ouachita  Mountains,  and 
southern  Arkansas.  They  are  generally  associated  with  sand- 
stones or  cherty  limestones.  The  first-named  district  makes  the 
best  showing.  In  it  the  ores  are  in  Lower  Silurian  (Calciferous  or 
lower)  sandstones,  cherts,  and  limestones.  In  the  second  district 
they  are  in  Lower  Silurian  cherts  and  Lower  Carboniferous  sand- 
stones. In  the  third,  they  occur  with  Carboniferous  and  Lower 
Carboniferous  strata,  but  are  also  in  the  form  of  recent  spring  de- 
posits. In  the  Ouachita  Mountains  they  are  with  Lower  Silurian 
shales  and  novaculites.  In  this  district  the  magnetite  of  Magnet 
Cove  occurs,  but  it  is  only  an  interesting  mineral  and  not  in  any 
practical  quantity.  The  last  district  has  the  ores  in  sands  and 
clays  of  the  Eocene.  Its  continuation  in  -Texas  and  Louisiana  has- 
been  already  mentioned  in  the  main  text. 

Page  122.  Too  little  attention  was  given  to  titaniferous  mag- 
netite in  the  text ;  for  although  these  ores  are  not  now  of  value, 
they  are  exciting  considerable  attention  and  are  of  great  scientific 
interest.  They  are  almost  invariably  in  wall  rock  that  consists  of 
plagiocla&e,  with  augite,  hypersthene,  and  hornblende,  one  or  all. 
The  rock  may  thus  be  gabbro,  norite,  or  diorite,  and  is  of  igneous- 
(plutonic)  character.  The  ores  appear  to  be  excessively  basic  de- 
velopments of  the  wall  rock,  which  were  formed  during  its  cooling 
and  crystallization.  Subsequent  metamorphism,  mountain-making 
processes  and  the  like,  sometimes  give  them  a  gneissic  structure, 
and  stretch  out  the  ore  into  apparent  beds.  In  the  great  series 
of  these  labradorite  rocks  which  is  so  extensive  in  Canada,  and 
which  was  called  by  T.  Sterry  Hunt  the  Norian,  these  ores 
are  very  abundant.  The  same  rocks  form  the  central  Adiron- 
dacks  and  contain  some  enormous  bodies  of  titaniferous  ore. 
Prof.  E.  Emmons  of  the  New  York  Geological  Survey  in  1835-40 
gives  much  space  to  them  as  occurring  near  Lake  Sanford  and 
Lake  Henderson.1  The  later  Survey  of  Uno  Sebenius  has  indi- 
cated an  even  greater  extent  than  was  known  to  Emmons,  although 


1  E.  Emmons,  Rep.  on  Second  District,  N.  Y.  State  Survey,  pp.  244- 
255,  1842.  A.  J.  Kossi,  "  Titaniferous  Ores  in  the  Blast  Furnace,"  Trans. 
Amer.  Inst.  Min.  Eng.,  February,  1893.  J..C.  Smock,  Bulletin  of  A'.  F. 
State  Museum,  p.  37. 


232  KEMP'S  ORE  DEPOSITS. 

that  was  over  500  feet  wide  and  1600  feet  long.  Numerous  other 
less  extensive  ore  bodies  also  occur  in  the  neighborhood,  and  very 
many  elsewhere  in  the  mountains.  They  are  all  titaniferous,  al- 
though, as  often  happens  with  such  ores,  they  are  low  in  phosphorus 
and  sulphur  and  at  times  quite  high  in  alumina.  At  present 
they  are  not  utilized,  but  it  is  to  be  hoped  that  in  time  processes 
will  be  developed  to  treat  them.  Fairly  high  titaniferous  ores  oc- 
<jur  in  New  Jersey  on  Schooley's  Mountain  and  to  the  southwest, 
and  small  amounts,  say  up  to  \%  of  TiO2,  are  known  in  many 
others.1  The  wall  rock  of  these  ores  should  receive  microscopic 
examination  to  determine  if  it  affords  a  mineralogical  parallel  with 
those  of  the  Adiroridacks. 

Titaniferous  ores  are  also  known  in  Virginia  and  North  Caro- 
lina,2 in  the  gabbros  of  Minnesota,  in  Wyoming,  in  Colorado — the 
last  three  of  which  have  already  been  mentioned  in  the  text. 
Microscopic  determinations  of  the  wall  rock,  where  not  already 
made,  would  be  of  great  interest.  Their  geological  relations  have 
long  been  known  in  Sweden  and  Norway,  but  an  igneous  form  of 
origin  has  been  but  recently  advocated.  (Cf.  p.  56.) 

Page  130.  In  the  review  of  the  methods  of  formation  of  mag- 
netite-lenses, the  method  by  segregation  or  as  segregated  veins 
was  omitted.  As  it  is  viewed  with  favor  by  many  reliable  observ- 
ers, it  should  have  its  place.  By  this  method  the  iron  oxide  is  con- 
ceived to  concentrate  from  a  state  of  dissemination  in  the  walls  by 
slow  secretion  in  solution,  to  form  the  ore  bodies  along  certain  favor- 
able beds.  The  action  is  regarded  as  analogous  to  the  formation 
of  concretions,  and  is  illustrated  on  a  small  scale  by  the  well-known 
disks  of  pyrite  and  calcite  that  form  in  clays  and  shales.  It  is  a 
curious  fact,  however,  that  some  magnetites  are  in  wall  rock  that 
hardly  shows  a  trace  of  even  a  dark  silicate.  Thus  the  lenses  at 
Hammondville,  in  the  Lake  Champlain  district,  are  in  a  pure,  white 
gneiss  that  only  has  a  little  garnet  near  the  ore,  but  it  is  possible 
that  elsewhere  the  explanation  may  be  the  most  reasonable  one. 
Where  it  applies  we  would  expect  hornblende  and  other  ferru- 
ginous minerals  in  the  walls. 

1  B.  F.  Fackenthal,  "  Titaniferous  Ores  in  the  Blast  Furnace,"  Trans. 
Amer.  Inst.  Min.  Eng.,  February,  1892.    R.  W.  Raymond,  Ibid. 

2  H.  B.  C.  Nitze,  "Notes  on  some  of  the  Magnetites  of  Southwest 
Virginia  and  the  Contiguous  Territory  of  North  Carolina,*'  Trans.  Amer. 
Inst.  Min.  Eng.,  June,  1891.    Reprint  p.  13.     See  also  discussion  of  the 
paper  at  the  same  meeting. 


f 

ADDENDA.  283 

Page  143.  The  limestones  called  the  Second  Magnesian,  and 
stated  to  be  of  Lower  Silurian  age  in  2.04.17,  have  been  lately 
shown  to  be  Cambrian.  (G.  C.  Broadhead,  "The  Correct  Succes- 
sion of  the  Ozark  Series,"  Amer.  Geol,  April,  1893,  p.  260.  F.  L. 
Nason,  "  The  Magnesian  Series  of  the  Ozark  Uplift,"  Ibid.,  Feb- 
ruary, 1893,  p.  91.  A.  Winslow,  "Notes  on  the  Cambrian  in 
Missouri,"  etc.,  Amer.  Jour.  ScL,  March,  1893,  p.  221.) 

Page  172.  C.  R.  Boyd  has  published  in  the  Engineering  and 
Mining  Journal,  June  17  and  24,  1893,  a  quite  complete  description 
of  the  lead  and  zinc  mines  and  works  of  the  Wythe  Company,  near 
Austinville,  Va.  The  geological  horizon  is  stated  to  be  in  the 
Knox  group  of  Safford,  which  is,  as  stated  in  the  text,  near  the 
Calciferous  of  New  York.  While  giving  a  thorough  historical 
sketch  and  description  of  the  works,  little  additional  to  the  brief 
outline  on  p.  172  is  given  on  the  geology. 

Page  247.  Mr.  Waldemar  Lindgrenhas  published  (June,  1893) 
in  the  Bulletin  of  the  Geological  Society  of  America,  Vol.  IV., 
pp.  257-298,  a  most  valuable  paper  on  "Two  Neocene  Rivers  of 
California."  He  traces  out  the  location  and  geological  history  of 
the  deep  gravels  along  the  drainage  line  of  the  American  and  Yuba 
rivers,  and  adds  much  to  our  knowledge  of  their  former  location 
and  gradients.  He  concludes  that  the  old  divide  in  general  coin- 
cided with  the  present  one,  but  that  the  slope  of  the  Sierra  has 
been  considerably  increase  1  since  the  time  when  the  Neocene  (i.e., 
Miocene  and  Pliocene),  ante-volcanic  rivers  flowed  over  its  surface. 
"  It  finally  appears  probable  .  .  .  that  the  surface  of  the  Sierra 
Nevada  has  been  deformed  during  this  uplift,  and  that  the  most 
noticeable  deformation  has  been  caused  by  a  subsidence  of  the 
portion  adjoining  the  great  valley,  relatively  to  the  middle  part  of 
the  range  "  (p.  298). 

General  Addenda.  I.  Through  the  courtesy  of  Dr.  R.  W. 
Raymond,  secretary  of  the  American  Institute  of  Mining  Engineers, 
the  author  has  been  permitted  to  read,  in  advance  of  its  pub- 
lication, the  great  essay  on  the  origin  of  ore  deposits,  that  Prof. 
Franz  Posepny  of  Vienna  has  sent  to  the  Institute  for  the  July 
meeting,  1893.  The  paper  is  a  theoretical  discussion  of  the  origin 
of  ores,  with  illustrations  selected  from  all  parts  of  the  world,  but 
especially  from  Europe  and  America.  It  forms  one  of  the  most 
important  contributions  to  the  literature  that  has  yet  been  made. 
Posepny  distinguishes  at  the  outset  between  rocks  and  mineral 
deposits  ;  i.e.,  between  original  materials,  such  as  wall  rock,  and 


284  KEMP'S   ORE  DEPOSITS. 

secondary  introductions,  such  as  veins,  etc.  The  former  he  calls 
"idiogenites,"  the  latter  "xenogenites,"  basing  the  names  on  the 
familiar  Greek  terms  that  run  through  all  our  literature.  The 
latter  are  especially  characterized  by  "  crustification,"  by  which 
term  is  indicated  what  has  been  termed  "  banded  structure,"  on  p. 
35.  The  subject  of  cavities  is  then  taken  up,  and,  while  minute 
pores  are  stated  to  be  in  all  rocks,  a  distinction  is  made  between 
the  larger  openings,  which  originate  in  a  rock  mass  as  a  part  of 
its  own  structure,  such  as  contraction  joints  in  igneous  rocks, 
amygdaloids,  and  the  like,  and  those  induced  by  outside  causes, 
such  as  fault  fissures. 

The  circulation  of  water  through  these  is  next  treated  :  first, 
surface  waters  or  "vadose"  circulations,  which  descend;  second, 
ascending  waters  from  great  depths,  such  as  springs  in  deep  mines, 
hot  springs,  etc.  The  common  salts  in  solution  in  these  latter  are 
tabulated,  being  of  course  mostly  alkaline  carbonates,  sulphates, 
chlorides,  etc.  The  "exotic"  metallic  admixtures  which  would 
bear  on  the  origin  of  ores  are  next  discussed,  so  far  as  possible 
with  analyses  of  actual  cases.  The  alterations  produced  by  miner- 
al springs  in  rocks  and  the  structural  relations  of  the  deposits  of 
mineral  springs,  especially  as  expressed  by  "  crustification,"  are 
then  described.  This  preliminary  material  clears  the  way  for  the 
general  discussion  of  the  origin  of  ore  bodies.  The  argument  run- 
ning all  through  the  paper  is  that  ore  bodies,  even  when  apparently 
interbedded  with  sedimentary  rocks,  are  of  secondary  introduction 
and,  in  general  for  veins,  are  from  deep-seated  sources.  Precipita- 
tion from  descending  solutions  and  filling  by  lateral  secretion  are 
strongly  controverted. 

The  discussion  of  origin  follows  in  its  arrangement  the  follow- 
ing classification  of  ore  deposits  : 

I.  Filling  of  spaces  of  discission  (fissures). 

II.  Filling  of  spaces  of  dissolution  in  soluble  rocks. 

III.  Metamorphic  deposits  in  soluble  rocks;  in  simple  sedi- 
ments ;  in  crystalline  and  eruptive  rocks. 

IV.  Hysteromorphic    (i.e.,    later   or   last    formed)     deposits. 
Secondary  deposits  due  to  surface  action  (i.e.,  placers,  etc.). 

The  treatment,  both  in  the  introductory  pages  and  in  the  later 
discussions,  is  often  strikingly  similar  to  that  of  this  book,  and  the 
underlying  argument  is  much  the  same.  The  standpoint  in  both 
essays  is  essentially  a  genetic  one,  and  the  main  difference  lies  in 
the  fact  that  the  one  is  an  exposition  of  an  individual's  views, 


ADDENDA.  285 

fortified  by  examples  from  all  parts  of  the  world;  the  other  en- 
deavors to  be  a  judicial  statement  with  a  complete  description  of 
the  ore  bodies  of  the  United  States  alone. 

II.  An  extended  treatise  on  the  useful  minerals,  earthy  as  well 
as  metallic,  by  M.  M.  E.  Fuchs  and  L.  De  Launay,  has  recently 
appeared  (Traite  des  Gites  Min&raux  et  M&talliferes,  Paris,  1893). 
The  book  is  based  on  the  lectures  in  economic  geology  delivered 
in  the  Ecole  Superieure  des  Mines,  at  Paris,  in  the  last  fifteen  years 
by  the  two  authors.  (Professor  Fuchs  died  in  1889,  and  was  suc- 
ceeded by  Professor  De  Launay.)  A  vast  amount  of  valuable  in- 
formation is  brought  together  and  discussed  from  various  points 
of  view,  useful  applications  and  methods  of  treatment  being  set 
forth  as  well  as  geological  occurrence.  So  far,  however,  as  the  ore 
deposits  and  other  useful  minerals  of  the  United  States  are  con- 
cerned, the  authors  have  suffered  from  the  unavoidable  limitations 
of  those  not  native  and  conversant  in  a  discriminating  way  with 
our  literature.  In  many  cases,  if  not  in  most,  the  descriptions  used 
by  them  are  from  German  or  other  foreign  sources,'  and  are  often 
antiquated  and  curiously  mixed.  While  placing  at  command  much 
that  is  not  easily  accessible  on  foreign  ore  deposits  and  those  in 
outlying  parts  of  the  world,  and  also  much  that  is  valuable  in  the 
way  of  general  discussion,  nevertheless  the  book  cannot  be  con- 
sidered in  its  American  relations  as  adding  much  to  our  literature. 


INDEX. 


Abiquin,  N.  M.,  copper  ores,  154. 
Adams,  F.  D.,  on  granite  at  Doug- 
lass Island,  255. 

Adirondack  titaniferous  ores,  280. 
Agglomerates,  200. 
Alabama,  Clinton  ore,  95,  96. 

Gold  mines,  252. 
Limonite,  78,  84. 

Tin,  274. 

Alaska,  geology,  253,  254. 
Aleutian  Islands,  25+. 
Algonia,  platinum,  272. 
Alice  mines,  Butte,  Mont.,  220. 
Alleghany  Mountains,  geology,  8. 
Alturas  Co.,  Idaho,  223. 
Aluminium,  258. 
Amador  Co.,  GJ!.,  249. 
American  River,  Cal.,  282. 
Ancram  lead  mine,  N.  Y.,  157. 
Anthony's  Nose,  nickel  mine,  270. 

Mine  of  pyrrhotite,  131. 
Anticlines,  11. 

Cause  of  cavities,  11. 
Antimony,  259,  260. 

Nevada,  232. 
Apache  Co.,  Ariz.,  228. 
Appalachians,  general  description,  6, 
7. 

Topography,  6,  7. 

Geology,  7,  8. 
Argentine,   Clear  Creek  Co.,  Colo., 

211. 
Arizona  copper  mines,  144-152. 

Geology,  227. 

Lead-silver  ores,  198. 

Prince    copper    mine,    Arizona, 
150. 

Silver  mines,  275. 
Arkansas,  antimony,  259. 

Bauxite,  258. 

Iron  ores,  279. 

Limonite,  Addenda. 

Manganese,  264-266. 

Nickel,  271. 

Silver  mines,  201. 
Arksut  Fjord,  Greenland,  258. 
Arlington,  N.  J.,  copper  mines,  153. 
Arnold  iron  mines,  N.  Y.,  122. 
Arsenic,  260. 


Ascension  by  infiltration,  29,  30-32. 
Ashcroft  iron  mines,  Colo.,  126. 
Aspen,  Colo.,  186-190,  211. 

Iron  mines  near,  126. 
Atlantic  copper  mine,  Mich.,  141. 
Augusta,  Va.,  manganese,  263. 
Auriferous  beach  sands,  240. 

Gravels,  243-248. 
Austin,  Nev.,  232. 

Antimony,  259. 

Austinville,  Va  ,  zinc  mines,  282. 
Bachelor    Mountain,    near    Creede, 

Colo.,  2U9. 
Baker  Co.,  Orp.,  239,  240. 
Bald  Butte  Co.'s  mines,  Mont.,  221. 
Baltimore,  Md  ,  chromite,  261. 
Banded  structure  of  veins,  35. 
Bannack  City,  Mont.,  219. 
Banner    district,    Boise   Co.,   Idaho, 

223. 

Bare  Hills,  Md.,  chromite  mine,  261. 
Barton  Hill  iron  mines,  N.  Y.,  121. 
Barus,  C.,  experiments  on  electrical 
activity  of  veins,  40,  41. 

Experiments  on    the    Comstock 

Lode,  235. 

Bassick  mine,  Colo.,  35,  36,  213. 
Batesville,  Ark.,  manganese,  265,  266. 
Bauxite,  258. 

Beach  sands,  form  of  ore  body,  58. 
Bear  Lake  Co. ,  Idaho,  223. 
Beaver  Co.,  Utah,  225. 
Beaverhead  Co.,  Mont.,  219. 
Becker,  G.  F..  precious  metals  in  dia- 
base, 25. 

Cited  on  Steamboat  Springs,  Nev., 
32. 

On  the  Comstock  Lode,  233-237. 

On  California  gravels,  247. 

On  California  mercury,  267-269. 

Various  metals  in  granite,  26. 
Beds,  in  sedimentary  rocks,  10. 
Belmont,  Nev.,  231,*232. 
Belts  of  ore  deposits  in  the  West,275> 

276. 

Berks  Co.,  Penn.,  iron  mines,  125. 
Bernalillo  Co.,  N.  M.,  204. 
Bertha  zinc  mines,  Wythe  Co.,  Va.,, 
172. 


.288 


INDEX. 


Bethlehem,  Perm.,  zinc  mines  near, 

174. 

Beulah  antimony  mine,  Nev.,  259. 
Big  Cottonwood  Canon,  Utah,  192. 
Big  Creek,  Nev.,  359. 
Bimetallic  mine,  Butte,  Mont.,  221. 
Bingham  Canon,  Utah,  192-225. 

Cited  as  illustration  of  gossan,  39. 
Bisbee  copper  district,  Ariz.,  148. 
Bismuth,  260,  261. 
Bitter  Root  Mountains,  Idaho,  222. 
Black-band  iron  ore,  87. 
Black  Copper  groups  of  copper  mines, 

Arizona,  150. 
Black  Hills,  geology,  9. 

Geology  and  mines,  216-218. 

Gold  in  Potsdam,  240. 

Placers,  245. 

Tin,  273. 

Black  Range  copper  mines,  Arizona, 
151. 

Copper  district,  228. 
Blake,  W.   P.,   on    the  Deep  Creek 
mines,  225. 

On  the  Silver  King  mine,  Arizona, 
228. 

On  Tombstone,  Ariz.,  229. 

On  Utah  antimony,  260. 

Ruby  silver  ore,  Poorm'an  lode, 

223. 

Block  iron  ore,  87. 
Block  Island,  R.  I.,  magnetite  sands, 

128. 

Blow,  A.  A.,  illustration  of  fault  by, 
17.     ' 

Cited  on  Leadville,  Colo.,  185. 
Bluebird  mine,  Butte,  Mont.,  221. 
Blue  lead  in  California  gravels,  246. 
Blue  Mountains,  Oregon,  239. 
Bog  iron  ore,  73. 

Precipitated  bv  algae,  75. 
Bog  ore  at  Three  Rivers,  279. 
Boise  Co.,  Idaho,  223. 
Bonanza  City,  Idaho,  223. 
Bonanza  of  ore,  37. 
Bonne  Terre,  Mo.,  lead  mines,  158. 
Bonneville,  Lake,  230. 
Bonsacks,  Va.,  illustration  of  gossan, 
39. 

Zinc  mines,  172. 
Boone  cherts,  Arkansas,  265. 
Boss  of  igneous  rock  defined,  11. 
Boston  Mountains,  Ark.,  265. 
Boulder  Co.,  Colo.,  214. 

Iron  ores,  126. 
Box  Elder  Co.,  Utah,  225. 
Boyd,  C.  R.,  on  Virginia  zinc  mines, 
'  282. 

Brandon,  Vt.,  manganese,  263. 
Bristol,  Conn.,  copper  mine,  153. 


British  Columbia  gold  gravels,  256. 

Platinum,  272. 
Britton,  N.  L.,  cited  on  the  geology  of 

the  Highlands,  N.  J.,  123. 
Broadhead,  G.  C.,  cited  on  Missouri 

geolosry,  282. 

Brooks,  T.  B.,  on  the  Marquette  dis- 
trict, 101,  102. 
Origin  of  ores,  106. 
Browne,  D.  H.,  on  phosphorus  in  iron 

mines,  130. 
Browne,  R.  E.,  on  California  gravels, 

246,  247. 

Brown  hematite,  Arkansas,  279. 
Brunton,    D.   W.,   cited    on    Aspen, 

Colo.,  188. 

Bucks  Co.,  Penn.,  iron  mines,  125. 
Buckwheat  mine,  Franklin  Furnace, 

N.  J.,  177. 

Buena  Vista,  Colo.,  212. 
Buford  Mountain,  Mo.,  116. 
Buhrstone  ore,  88. 
Bull  Domingo  mine,  Colo.,  36,  213. 
Burden  spathic  ore   mines,  Hudson, 

N.  Y.,  89. 

Burro  Mountains,  N.  M.,  203. 
Butte,  Mont.,  220. 

Copper  mines,  136, 137,  142. 
Illustrates  infiltration  by  ascen- 
sion, 32. 

Placers  near,  245. 
Calaveras  Co.,  Cal.,  249. 
Caldwell  Co.,  Ky.,    lead    and    zinc 

mines,  166. 

Calico  district,  Cal.,  242. 
California,  Chromite,  261. 
Copper  mines,  136. 
Literature,  136. 
Geology,  241. 
Gulch,  near  Leadville,  Colo.,  211, 

245. 

Kern  Co.,  antimony,  259. 
Lead-silver  ores,  198. 
Magnetite,  126. 
Mercury,  267,  268. 
Platinum,  272. 
Tin,  274. 

Yuba  and  American  rivers,  282. 
Gallon  scheme    of    classification    of 

ore  deposits,  47. 
Calumet    and    Hecla  copper    mines, 

Michigan,  141. 
Iron  mine,  Colorado,  126. 
Campbell    Mountain     near     Creede, 

Colo  ,  209. 

Campo  Seco,  Cal.,  copper  mines,  136. 
Canada  bog  ores,  279. 
Gold,  255,  256. 
Magnetite  ore  mines,  122. 
Titaniferous  magnetite,  280. 


INDEX. 


289 


Canso,  N.  S.,  255. 

Cape  Breton,  N.  S.,  manganese,  266. 

Capelton,  Quebec,  mines  of  pyrite, 

131;  chalcopyrite,  134. 
Carbonate  Hill,  L^adville,  Colo.,  183. 
Carbonate  mine,  Utah,  195. 
Carpenter,  F.  E.,  on  the  Black  Hills, 

S.  D.,217. 

On  Black  Hills  tin,  274. 
Carson  Hill,  Calaveras  Co.,  Cal.,  248. 
Cartersville,  Ga.,  manganese,  263. 
Cascade  Mountains,  238. 
Cascade  Range,  Cal.,  241. 
Cassia  Co.,  Idaho,  223. 
Casbiterite,  273. 

In  granite  veins,  60. 
Cave  mine,  Utah,  195. 
Caves,  origin  of,  21. 

As  a  form  of  ore  body,  57. 
Cave  Spring  manganese  mines,  Geor- 
gia, 263. 
Cazin,  F.  M.  F.,  on  Silver  Reef,  Utah, 

226. 

Cedar  Mountain,  Mo.,  116. 
Central  City,  Colo.,   copper    mines, 

138. 
Chaff ee Co.,  Colo.,  212. 

Magnetite,  126. 
Chalcopyrite  with  pyrite,  134-136. 

Literature,  135. 
Chamberlain,   S.    C.,    on    Wisconsin 

lead  and  zinc  mines,  161-163. 
Chambered  vein,  267. 
Charlemont,  Mass.,  mines  of  pyrite, 

131. 

Charles  Dickens  mine,  Idaho,  223. 
Chatham,  Conn.,  nickel  mine,  270. 
Chateaugay  iron  mines,  New  York, 

72,  120. 

Chaudiere  River,  Canada,  gold,  256. 
Chauvenet,  R. ,  cited  on  Colorado  iron 

ores,  126. 
Chester,  A.  H.,  on  the  average  yield 

of    certain     well-known    iron 

ores,  71. 

Chicago  Coppermine,  Arizona,  150. 
Chico  beds,  California,  267. 
Chimney  of  ore,  37. 
Chromite  distribution,  261. 
Chromium,  261. 

Mines,  California,  275. 
Chug  water  Creek,  Wyo.,   iron  ores, 

126. 
Church,  J.  A. ,  on  the  Comstock  Lode, 

233,  234. 

Churchill  Co.,  Nev.,  232. 
Chute  of  ore,  37. 
Cincinnati  uplift,  9. 
Cinnabar,  267. 
Classification  of  ore  deposits,  42-62. 


Classification  of  ore  deposits,  under- 
lying principles,  42. 

Wadsworth,  278. 
Clay  ironstone  defined,  86. 

Deposits  of,  86-88. 
Clay  selvage,  seam,  or  parting,  37. 

Attrition  clay,  37. 

Residual  clay,  37. 

Clayton,  J.  E.,  on  Butte,  Mont.,  220. 
Clayton's  law,  37. 

Clear  Creek  Co.,  Colo.,  211,  212,  214. 
Clear  Lake,  Cal.,  mercui'3T,  267. 
Clerc,  F.  L.,  cited  on  zinc  mines  of 
southwestern  Missouri,  167-170. 
Cliff  copper  mine,  Michigan,  141. 
Clifton,  Ariz.,  copper  district,  145. 
Clinton  ore,  92-98. 

Distribution,  92-97. 

Origin,  97. 

Clinton  ores,  general  relations,  276. 
Coal    measures,    classification  of  in 

Pennsylvania,  87. 
Coastal  Plain,  252. 

Geology,  8. 

Topography,  6. 
Coast  Range  b*-lt  of  mines,  275. 

Chromite,  261. 

Oregon,  39. 

Washington,  238. 
Cobalt,  262. 

Cochise  C->.,  Ariz.,  229. 
Cceur  d'Alene,  Idaho,  lead-silver  ores, 

192. 

Col  fax  Co.,  N.  M,  204. 
Colombia,  platinum,  272. 
Colorado,  geology,  204. 

Iron  (bog)  ore,  74. 

Lead-silver  mines,  182,  191,  275. 

Limonite,  79. 

Magnetite,  126. 

Literature,  126. 

Plateau,  7-9. 

Silver  and  gold,  205-216. 

Spathic  iron  ore,  89. 

Titaniferous  ores,  281. 
Columbia  Co.,  N.  Y.,  lead  mines,  157. 
Columbia  Hill,   gravels,    California, 

245. 

Comb-in-comb  structure  in  a  vein,  35. 
Comstock  Lode,  Nev.,  233-237. 
Comstock,  S.  B.,  on   Red  Mountain, 
Colo.,  190. 

On  vein  systems  of  the  San  Juan, 

206. 

ConejosCo.,  Colo.,  212. 
Connecticut,  bismuth,  260. 

Lead  mines,  157. 

Limonite,  80,  85. 

Magnetite  sands,  128. 

Roxbury  siderite,  91. 


290 


INDEX. 


Contact  deposits,  58. 

Copper  Basin,  Ariz.,  151. 

Copper  Creek,  near  Gothic,  Colo.,  211. 

Copper  Falls  copper  mine,  Michigan, 

141. 

Copper  Mountain,  Ariz.,  copper  dis- 
trict, 145. 

Copperopolis,  Cal.,  copper  mines,  136. 
Copperopolis  copper  mine,  Utah,  152. 
Copper  ores,  analyses  of  ore  miner- 
als, 134. 

Capper  Queen  mine,  Arizona,  150. 
Copper,  statistics,  155. 
Cordillera  region,   general  geology, 

27o. 
Cornwall,  Penn.,  iron  mines,  125, 127. 

Literature,  127. 

Costillo  Co.,  Colo.,  iron  mines,  126. 
Cotta,  B.  von,  on  filling  of  mineral 

veins,  28. 
Schemes  of  classification  of  ore 

deposits,  44-46. 
Courtis,  W.  M.,  on  the  microscopic 

structure  of  gold  quartz,  249. 
Cranberry  magnetite  mines,   North 

Carolina,  125. 
Credntr,  H ,  on  origin  of  Marquette 

ores,  106. 

Creede,  Colo.,  207-209. 
Crimora,  Va.,  manganese,  263. 
Crismon-Mammoth      copper      mine, 

Utah,  152,  194. 
Crittenden  Co.,  Ky.,  lead  and  zinc 

veins,  166. 

Crosby,  W.  O.,  cited  on  joints,  13. 
Cross,  W.,  on  the  mines  near  Rosita, 

Colo.,  213. 
Crustification,  283. 
Cryolite,  258. 

Cumberland  iron  mine,  Colorado,  126. 
Cumberland  River  region,  Kentucky, 

78. 

Curry  Co.  ore,  240. 
Curtis,  J.  S.,  cited  on  caves,  21. 
On  Eureka,  Nev.,  196,  197. 
On  growth  of  aragonite  crystals, 

34. 

On  replacement,  33. 
On  silver  in  quartz  porphyry,  25. 
Caster  Co.,  Colo.,  212,  213. 

Idaho,  223. 

Custer  mine,  Idaho,  223. 
Dakyns  and  Teall  cited  on  origin  of 

magnetite,  129. 
Dall,  W.  H.,  on  Alaska,  253. 
Dana,  divisions  of  geological  time,  4. 
Davison  Co.,  N.  C.,  lead  mines,  157. 
Dawson,  G.  M..  on  Douglass  Island, 

254. 
Deadwood,  S.  D.,  217. 


Deep  Creek  mine^,  Utah,  225. 
Deep  gravels,  California,  24o. 
Deer  Lodge  Co.,  Mont.,  221. 
Deer  Trail  mine,  Utah,  226. 
De'la  Biche,   electrical    activity  of 

veins,  41. 

De  Launay,  treatise  of,  285. 
Delaware,  chrornite,  261. 
Del  Noi-te  Co.,  Cal.,  chromite,  261. 
Deloro,  Can.,  arsenic  mine,  260. 
Deloro  (Marmora),  Can.,  gold  mine* 

256. 
Devereux,  W.  B.,  cited  on  Colorado 

iron  ores,  126. 
Devonian  system  at  Hamilton,  Nev., 

231. 

Diaclases.    See  under  "  Joints." 
Dickerson  iron  mine,  New  Jersey,  130. 
Dike  defined,  11. 

Distinction  from  vein,  11. 
Cause  of  earthquakes,  17. 
Diller,  J.  S.,  cited  on  Kentucky  peri- 

dotite,  166. 
On  California,  241. 
Dillsburg  iron  mines,  Pennsylvania^ 

127. 

Doe  Run,  Mo.,  lead  mines,  158. 
Dolomitization,  21,  22. 
Dolores  Co.,  Colo.,  205. 
Dofia  Ana  Co.,  N.  M.,  181. 
Douglass  Co.,    Ore.,    nickel    mines,. 

271. 

Douglass  Island,  Alaska,  250,  254. 
Drinker,  H.  S. ,  cited  on  the  Saucon 

Valley  zinc  mines,  175. 
Drumlummon  mines,  Montana,  221, 

222. 

Dry  Canon,  Utah,  194,  225. 
Ducktown,  Tenn.,  illustration  of  gos- 
san, 39. 
Mines  of  pyrite  and  chalcopyrite, 

131,  135. 
Dutton,   Capt.  C.  E.5   cited    on  the 

geology  of  New  Mexico,  203. 
Dyestone  iron  ore,  92. 
"  Dvestone  ranges,'  94. 
Eagle  Co.,  Colo.,  211. 
Eagle  River  district,  Colo.,  186. 
Earth,  average  composition  of  crust, 

72. 
Eastern  sandstone,  Keweenaw  Point, 

Mich.,  139. 

Egan  Canon,  Nev. ,  231. 
El  Dorado  Co.,  Cal.,  249. 
Electrical  activity  of  ore  bodies,  235 1 

of  veins,  40. 
Elk  Mountains,  Colo.,  211. 

Iron  mines,  126. 
Elko,  Nev.,  231. 
Elko  Co.,  Nev.,  232. 


INDEX. 


291 


Ely  copper  mines,  Vermont,  134,  135. 

Emma  mine,  Utah,  194. 

Emmons,  E.,  on  Adirondack  titanif- 

erous  ores,  280. 

Emmons,  S.  F.,  cited  on  replacement, 
33. 

On  Butte,  Mont.,  137. 

On  country  rock  of  Boulder  Co. , 
Colo.,  214. 

On  Leadville,  Colo.,  183-185. 

On  Red  Mountain,  Colo.,  190. 

On  the  mines  near  Rosita,  Colo., 

213. 
Endlich.  F.  M.,  on  gold  mines  near 

Ouray,  Colo.,  206. 
Enterprise,  Miss.,  spathic  ore,  89. 
Esmeralda  Co.,  Nev.,  232. 
Etta  granite  knob,  with  tin  ore,  273. 
Eureka  Co.,  Nev.,  232. 

Electrical  activity  of  ore,  235. 

Illustration  gossan,  39. 

Lead-silver,  196. 

Evigtok,  Greenland,  cryolite,  258. 
Fahlbands  denned,  61. 
Fairplay,  Colo.,  212,  245. 
Farish,  J.  B.,  illustration  by,  20. 

On  the  veins   at  Newman  Hill, 

near  Rico,  Colo.,  206,  207. 
Faults,  cause  of,  13. 

Defined  and  described,  17-20. 

Hade,  17. 

Normal,  18. 

Reversed,  18. 

Schmidt's  law  of,  18. 

Step  faults,  20. 
Feather  River,  Cal.,  241. 
Felch  Mountain  area  and  iron  ores, 

Michigan,  104. 

Fisher  Hill  iron  mines,  New  York,  121. 
Flagstaff  mine,  Utah,  194. 
Flagstone  iron  ore,  87. 
EJaxseed  iron  ore,  92. 
Flotz  denned,  43. 
Floyd  Co.  (Ga.)  bauxite,  258. 
Flucan  of  a  vein,  37. 
Foerste,  A.  F.,  on  Clinton  ore,  97. 
Folds,  various  kinds  defined,  11. 

Axes  of,  11. 

Cause  of  cavities,  13. 

"Pitch  "of,  11. 
Forest  of  Dean  iron  mine,  New  York, 

123. 
Forest  Queen   mine,  Ruby   district, 

Colo.,  211. 

Formation  defined,  5. 
Fort  Laramie,  Wyo.,  iron  ore  near, 

114. 

Fossil  iron  ore,  92. 
Foster  and  Whitney,  cited  on  Mar- 
que tte  district,  101. 


Foster  and  Whitney,  Marquette  dis- 
trict, origin  of  its  ores,  104. 

On  Keweenaw  Point  copper,  142. 
Fouque  and  Levy  cited,  279. 
Franklin    copper    mines,    Michigan, 

141. 
Franklin    Co.    (Mo.)    lead  and    zinc 

mines,  165. 

Franklin  Co.  (Va.)  magnetite,  125. 
Franklin,  N.  J.,  123. 
Franklin  Furnace,  N.  J.,  174, 175-179. 

Iron  mines,  124. 
Franklinitp,  262. 

Freeland,  F.  T.,  cited  on  faults,  19. 
Fremont  Co.  (Colo.)  magnetite,  126. 
Friedensville  zinc  mines,  Penn.,  174. 
Frisco,  Utah.  195. 
Frost  drift,  North  Carolina,  252. 
Fryer  Hill,  Leadville,  Colo.,  183. 
Fuchs  and   Le  Launay,  treatise   of, 

284. 
Fulton,  J.,  on  the  Menominee  district, 

107,  108. 

Gagnon  vein,  Butte,  Mont.,  137. 
Galena    (town),    S.    D.,     lead-silver 

mines,  191. 
Gangue  minerals  forming,  23. 

Source  of,  26. 

Gap  mine,  Lancaster  Co.,  Penn.,  270. 
Gap    mine    of    pyrrhotite,   Pennsyl- 
vania, 131. 
Gatling  arsenic  mines,  Deloro,  Can., 

260. 

Genesee  antimony  mine,  Nevada,  259. 
Genth,  F.  A.,  on  Boulder  Co.,  Colo., 
214. 

On  gold  in  Southern  States,  252. 
Geology,  modern  standpoints,  3. 

Tabulation  of  geological  subdi- 
visions, 4,  5. 
Georgetown,  Colo.,  214. 
Georgia,  bauxite,  258. 

Clinton  ore,  95. 

Limonite,  84. 

Manganese,  263. 

Geyser  mine,  Custer  Co.,  Colo.,  213. 
Gilbert,  G.  K.,  cited  on  joints,  13. 

Illustration  loaned  by,  15. 
Gilpin  Co.,  Colo.,  214,  250. 

Banded  veins,  35. 

Copper  mines,  138. 
Glendale,  Mont.,  219. 

Lead- silver  ores,  191. 
Glenmore  estate,  West  Virginia,  98. 
Globe  copper  district,  Arizona,  150, 

228. 

Gogebic  district  of  Lake  Superior,  108. 
Gold,  Alaska,  254,  255. 

Black  Hills,  217. 

California,  243-250. 


000 

/v  *//*/ 


INDEX. 


Gold  in  sea  beaches,  240. 
Nova  Scotia,  255. 
Occurrence  and  ores,  200. 
Oregon,  240. 
Quartz  veins,  248. 
Southern  States,  252. 
Statistics,  256. 
Washing-ton,  239. 

Gold  Cup  mine,  Tin  Cup,  Colo.,  211. 
Gossan,  38. 
Gothic,  Colo.,  211. 
Gouge  of  clay  in  a  vein,  37. 
Graham  Co.,  Ariz.,  229. 
Granby,   Mo.,  zinc  and  lead    mines 

near,  166-171. 

Grand  Canon  of  the  Colorado,  227. 
Granite,  Chaffee  Co.,  Colo..  212. 
Granite  Mountain  mine,  Butte,  Mont., 

221. 

Granite  veins  with  cassiterite,  60. 
Grant  Co.,  N.  M.,  203. 
Grant  Co.,  Ore.,  240. 
Great  Basin,  3-7,  10. 
In  California,  241. 
In  Oregon,  239. 

Great  Eastern  mercury  mine,  267. 
Great  Lakes,  geology,  8,  9. 
Great  Valley,  8,  276. 
Iron  ores  of,  79. 

Great  Western  mercury  mine,  267. 
Greeneyed  Monster  mine,  Utah,  226. 
Greenland  cryolite,  258. 
Green  Mountain  placers,  245. 
Green  River,  Utah,  224. 
Greisen  with  tin  ores,  273. 
Griffin,  P.  H.,  on  bog  ores  of  Quebec, 

279. 
Grimm,  J.,    scheme  of  classification 

of  ore  deposits,  50. 

Groddeck,  A.  v.,  scheme  of  classifica- 
tion of  ore  deposits,  51. 
Gulf  region,  geology,  9. 
Gunnison  Co.  (Colo.)  iron  mines,  126. 
Gunnison  region,  Colorado,  211. 
Hade  of  a  fault,  17. 
Hag'ue,  A.,  cited  on  Wyoming  iron 

ore,  126. 

On  Hamilton,  Nev.,  231. 
Hague,  A.,  and  Iddings,  J.  P.,  on  the 

Comstock  Lode,  233,  236,  237. 
Haile  grold  mine,  South  Carolina,  252. 
Hall,  C.  E.,  cited  on  the  iron  mines  of 

the  Adirondacks,  122. 
Hamilton,  Nev.,  231. 
Hammondville  (N.   Y.)  iron  mines, 

122. 
Hampton  and  Eureka  copper  mines, 

Arizona,  151. 
Hancock,  Mich.,  139. 
Hanging  Rock  region  of  Kentucky,  77. 


Hanging  Rock    region    of    limonite 

ores,  77. 

Spathic  ores,  88. 
Harrington,  B.  J.,  cited  on  the  origin 

of  magnetite,  130. 
Hartman  zinc  mine,    Pennsylvania, 

174. 

Hastings  Co.,  Can.,  260. 
Haworth,  E.,  cited  on  zinc  and  lead 

ores  of  southwestern  Missouri, 

170. 

Hayes,  C.  W.,  illustration  by.  18. 
Hecla  iron  mine,  Colorado,  126. 
Hecla  mines,  Glendale,  Mont.,  191. 
Hecla  mines,  Montana,  219. 
Helena,  Mont..  221. 
Hematites,  red  and  specular,  table  of 

analyses.  118. 
Henderson  Lake,  N.  Y.,  titaniferous 

ores.  280. 

Henrich,  C.,ci'ed  on  Aspen,  Colo. ,189. 
On  Clifton  (Ariz.)  copper  mines, 

146. 

On  the  Slayback  lode,  New  Mexi- 
co, 204. 

Henry  Co.,  Va.,  magnetite,  125. 
Hesse,  Germany,  bog  ore,  75. 
Hibernia  iron  mines,  New  Jersey,  124. 
High  or  deep  gravels,  California,  245. 
Hills,  R.  C.,  cited  on  the  chemistry 

of  replacement,  34. 
On  the  Little  Annie  mine,  Colo., 

212. 
On  the  win  systems  of  the  San 

Juan,  206. 
Zone  of  enrichment  in  the  mines 

of  the  Summit  district,  Colo., 

39,  40. 

Hinsdale  Co.,  205. 
Hoefer,  H.,  cited  on  faults,  19. 
Hogan  Mountain,  Mo.,  116. 
Homestake  mine,    Eagle  Co.,   Colo., 

211. 

Honorine  mine,  Utah,  194. 
Horizon  defined,  5. 
Horn  Silver  mine,  Utah,  195. 
Horses  of  barren  rock  in  a  vein,  36. 
Hot  Springs  iron  mines,  Colorado,, 

126. 

Huerfano  Co.,  Colo.,  212. 
Humboldt  Co.,  Nev.,  232. 

Antimony,  259. 
Humboldt-Pocahontas    mine,  Custer 

Co.,  Colo.,  213. 
Humboldt  range,  Nev.,  231. 
Hunt,  T.  S.,  on  Canadian  titaniferous 

ores,  280. 

On  the  iron  mines  of  the  Adiron- 
dacks, 122. 
Hard  iron  mines,  New  Jersey,  124. 


INDEX. 


293 


Hysteromorphic  deposits,  284. 

Ibapah  range,  Utah,  225. 

Ice,   veins  of,  on  Mount   McClellan, 

Colo.,  211. 
Idaho,  geology,  222. 

Lead-silver  ores,  191,  192. 
Tin,  274. 

Idaho  Springs,  Colo.,  214. 
Iddings,  J.  P  ,  on  basaltic  columns, 

12. 
On  the  Comstock  Lode,  233,  236, 

237. 

Idiogenites  of  Posepny,  284. 
Igneous  rocks,   defined  and  roughly 

classified,  6. 
Forms  assumed  by,  11. 
Illinois  lead  and  zinc  mines,  161. 
Independence,  Colo.,  211. 
Ingersoll  granitic  knob,  with  tin  ore, 

273. 

International  Geological  Congress, 
1885,  c  assiflcation  recommend- 
ed by,  3,  4. 

Inyo  Co.,  Cal.,  antimony,  259. 
Iowa  lead  and  zinc  mines,  161. 

Limonite,  79. 
Ireland,  bog  ore,  75. 
Iridium,  with  platinum,  272. 
Iron  Co.,  Utah,  226. 
Magnetite,  128. 

Literature,  128. 
Iron  hat,  38. 

Iron  Hill,  Leadville,  Colo.,  183. 
Iron  in  rocks,  72. 

Iron  King  iron  mine,  Colorado,  126. 
Iron  Mountain,  Colo.,  126. 
Iron  Mountain,  Missoula  Co.,  Mont., 

222. 

Iron  Mountain,  Mo.,  116,  130. 
Bibliography,  118,  119. 
Illustration  of  subae' rial  decay,  59. 
Porphyries.,  117. 
Iron    ores,   bibliography  of    general 

papers,  69. 

Brown  hematite  ore,  73-85. 
General  remarks  on,  70-73. 
Impurities,  71. 

Iron  ore,  magnetite,  119-130. 
Iron  ore  localities  : 

Adirondack  Mountains,  120-122. 
Alabama,  78,  84. 

Clinton  ore,  95,  96. 
Arkansas,  Addenda. 
Colorado,  79,  89. 

Hall's  Valley  and  Handcart 

Gulch,  Park  Co.,  74. 
Connecticut,  80-85,  91. 
Georgia,  84. 

Clinton  ore,  95. 
Hesse,  Germany,  75. 


Iron  ore  localities : 
Iowa,  79. 
Ireland,  75. 
Kentucky,  77,  78,  88. 

Clinton  ore,  93. 
Louisiana,  79. 
Maryland,  82. 

Clinton  ore,  94. 
Massachusetts,  80-84,  89. 
Michigan  78. 

General  outline,  100. 

Marquette  district,  102-105. 

Menominee  district,  107, 108. 

Penokee-Gogebic  district,  108. 
Minnesota,  78. 

Vermilion  district,  110,  111. 

Mesabi  range,  111. 
Missouri,  78. 

Cambrian,  99. 

Iron  Mountain,  116. 

Lower  Carboniferous,  98. 

Pilot  Knob,  114. 
Mississippi,  89. 
Montana,  89. 

Great  Falls,  74. 
New  Jersey,  81. 
New  York,  80,  85, 

Burden  Mines,  89. 

Clinton  ore,  93. 

Jefferson  Co.,  99. 

Rye,  74. 

Staten  Island.  74. 

Wawarsing,  91. 
North  Carolina,  74,  84,  89. 

Specular,  114. 

Nova  Scotia,  Clinton  ore,  97. 
Ohio,  78,  88. 

Clinton  ore,  92,  93. 
Oregon,    Port    Townsend  Bay, 

Portland,  74,  75. 
Pennsylvania,  87. 

Adams  Co.,  85. 

Blair  Co  ,  77. 

Carbon  Co.,  77. 

Franklin  Co.,  76,  77. 

Fulton  Co.,  77. 

Huntingdon  Co.,  76,77. 

Juniata  Co.,  77. 

LehighCo.,  81,  84. 

MifflinCo.,77. 

Perry  Co.,  77. 

York  Co.,  81,84,  85. 

Clinton  ore,  93. 

Mansfield  orps,  98. 
Quebec,  Three  Rivers,  Addenda. 
Tennessee,  78,  82. 

Clinton  ore,  94. 
Texas,  78. 
Utah,  79. 
Vermont,  80. 


294 


INDEX. 


Iron  ore  localities : 
Virginia,  77-82. 
Clinton  ore,  94. 
Specular,  113. 
West  Virginia,  88. 
Clinton  ore,  94. 
Oriskany  ore,  98. 
Wisconsin,  Clinton  ore,  92. 

Menominee  district,  107,  108. 
Penokee  -  Gogebic      district, 

108,  109. 
Wyoming,  89. 
Iron  ore,  pyrite,  131,  132. 

Red  and  specular  hematite,   92- 

119. 
Iron  ores,  origin  of,  278. 

Siluro-Cambrian  limonites,  79-85. 
Spathic,  86-91. 
Statistics,  133. 
Swedish  lakes,  75. 
Table  of  and  compositions,  70. 
Irving  and  Van  Hise  on  the  Marquette 

district,  101,  102. 
Origin  of  the  ores,  106. 
Irving,  R.  D.,  cited  on  Silver  Islet, 

202. 

On  replacement,  33. 
Penokee-Gogebic  district,  109. 
Ishpeming,  Mich.,  gold,  253. 
Isle  Royale,  Lake  Superior,  139,  141, 

143. 

Izard  limestone,  265. 
Jackson  Co.,  N.  C..  nickel,  271. 
Jacque  Mountain,  Summit  Co.,  Colo., 

211. 

Jackson,  Ore.,  nickel,  271. 
James  River,  Va.,  specular  ores  near. 

113. 
Jasper  Co.  (Mo.)  zinc  and  lead  mines, 

*  167. 

Jay  ville  iron  mines,  New  York,  122. 
Jefferson  Co.,  Mont.,  219. 
Jefferson    Co.   (Mo.)    lead    and    zinc 

mines,  165. 
Jenney,  W.    P.,  cited  on  Arkansas 

silver  mines,  201. 
On  lateral  enrichments,  37. 
On  lead  ores  of  southeastern  Mis- 
souri, 159. 
On  lead  and  zinc  mines  of  the 

Mississippi  Valley,  164. 
On  mines  of  Mississippi  Valley, 

276. 

On  the  Head  Center  mine,  Tomb- 
stone, Ariz.,  31. 

On  zinc  and  lead  mines  of  south- 
western Missouri,  170. 
Joints  defined,  12. 

Joplin  (Mo.)  zinc    and  lead  mines, 
166-171. 


Josephine  Co.,  Oregon,  240. 

Juab  Co.,  Utah,  225. 

Julien,  A.  A.,  action  of  organic  acids 

on  rocks,  21. 
Cited  on  the  origin  of  magnetite, 

130. 

Kansas,  nickel,  271. 
Kaolin  ization  at  the  Comstock  Lode, 

235. 

Kelley  Lode,  New  Mexico,  181. 
Kemp,  J.  F.,  scheme  for  the  clas^ifi- 

cation  of  ore  deposits,  53-55. 
On  Missouri  lead  deposits,  159. 
Kentucky,  lead  and  zinc  ores  of  Liv- 
ingston Co.,  165. 
Clinton  ore,  93. 
Limonite,  77,  78. 
Limonite  or  brown  hematite  ores, 

77,  78. 

Spathic  ores,  88. 
Kern  Co.  (Cal.)  antimony,  259. 
Kerr,  W.  C.,  on  North  Carolina  gold, 

252. 
Keweenaw  Point  (Mich.)  copper,  139- 

143. 
Kimball,  J.  P.,  cited  on  the  Burden 

mines,  New  York,  89. 
On  origin  of  iron  ores,  278. 
King,  C.,  on  the  Comstock  Lode,  233, 

234. 

Kinahan,  J.  H.,  cited  on  joints,  13. 
Kittitas  Co.,  Washington,  gold,  238. 
Klausen  in  the  Austrian  Tyrol,  veins 

illustrating   lateral    secretion, 

31,  32. 

Knob  of  igneous  rock  defined,  11. 
Koehler,  G.,  cited  on  faults,  19. 

Scheme   of  classification  of  ore 

deposits,  47. 
Lahontan,  Lake,  230. 
Laccolite  defined,  11. 
Lac  la  Belle,  Keweenaw  Point,  142. 
Lager    defined   as    contrasted    with 

"F16tz"and  "Gang,"  43. 
Lakes,  A.,  cited  on  Aspen,  Colo.,  189. 
Lake  Cham  plain  iron  region,  120. 

Magnetite  sands,  128. 
Lake  Co.,  Colo.,  211. 
Lake  of  the  Woods,  gold  district,  256. 
Lake  Superior  gold  region,  256. 
Iron  ore  districts,  100-113. 
Mines,  276. 
Lake  Valley  (N.  M.)  lead-silver  ores, 

181. 

Lancaster  Co.  (Penn.)  chromite,  261. 
Lander  Co.,  Nev.,  232. 

Antimony  mines,  259. 
Lander  Hill,  Nev.,  232. 
Lane's  Mine,  Monroe,  Conn.,  260. 
La  Plata  Co.,  Colo.,  205. 


INDEX 


295 


Lassens  Peak,  Cal.,  241. 

Last    Chance   Gulch,   near    Helena, 
Mont.,  221,  245. 

Lateral  enrichments  in  a  vein,  37. 
secretion,  29. 

Lead  City,  Black  Hills,  217. 

Leadville,  Colo.,  182-185. 

Figure  of  Moyer  Fault,  17. 

Lead  minerals,  156. 
Statistics,  160. 

Lead-silver  ores,  181. 

Leconte,   J.,  on    California  gravels, 

247. 

On  joints,  13. 
On  mercury  deposits,  California, 

267. 

Scheme  of  classification  of  veins, 
45. 

Lehigh     Co.     (Penn.)     iron    mines, 
magnetites,  125. 

Lenses,  or  lenticular  beds  of  ore,  ori- 
gin of,  59. 

Lesser  metals,  258-277. 

Lesquereux,  cited  on  California  grav- 
els, 246. 

Lewis  and  Clarke  Co.,  Mont.,  221. 

Lewis  Mountain,  Mo.,  116. 

Lime  Creek  (Colo.)    Lower  Carbon- 
iferous fossils,  189. 

Limonite,  Arkansas,  289. 

Limonite,  deposits  of,  73-86.  See  also 
under  iron  ore  for  geographical 
distribution. 
Analyses,  86. 

Lincoln  Co.,  Nev.,  230. 

Lincoln  Co.,  N.  M.,204. 

Lindgren  on  Wickes,  Mont.,  192. 

Lindgren,  W.,  on  Calico  district,  Cal., 

243. 

On  Neocene  rivers  of  California, 
282. 

Linnaeite,  269. 

Little  Annie  mine,  Rio  Grande  Co., 
Colo.,  212. 

Little  Belt  Mountains,  Mont.,  222. 

Little  Cottonwood  Canon,  Utah,  192. 

Little  River  iron  mines,  New  York, 
121. 

Little  Rock  (Ark.)  bauxite,  258. 

Livingston    Co.    (Ky.)  lead  and  zinc 
mines,  165. 

Uano  Co.  (Texas)  copper  mines,  139. 

Logan  Co.  (Kan.)  nickel,  271. 

Lottner-Serlo  scheme  of  classification 
of  ore  deposits,  47. 

Longdale  iron  mines,  Virginia,  77. 

Louisa  Co.  (Va.)  mines  of  pyrite,  131. 

Louisiana  lirnonite,  79. 

Lovelock  mines  (Churchill  Co.,  Nev.) 
nickel,  271. 


Lovelock,  Nev.,  259. 
Lowell  (Mass.)  nickel  mine,  270. 
Low  Moor  iron  mines,  Virginia,  78. 
Lowville    (Lewis    Co.,   N.   Y.)    lead 

mine,  157. 

Lubeck  (Me.)  lead  mine,  157. 
Lucky  Boy  mine,  226. 
Lyndhurst  (Va.)  manganese,  263. 
Lynchburg,  Va.,  iron  ores  near,  113. 
Lj^onCo.,  Nev.,  232. 
Lyon  Mountain  (N.  Y.)  iron  ores,  120. 
Mackenzie  River,  gold  gravels,  256. 
Madison  Co.,  Mont.,  219. 
Magdalena  Mountains,  N.  M.,  181. 
Magna  Charta  mine,  Butte,    Mont., 

220. 

Magnet  Cove,  Ark.,  magnetite,  280. 
Magnetite  iron  ore,  120-131. 

Analyses,  131. 

General  description,  120. 

Origin  of,  129. 

Origin  in  igneous  magmas,  56. 

Ore    bodies,     general    relations, 
276. 

Sands,  128. 
Maine  tin,  274. 
Manganese,  262-266. 

Statistics,  266. 

Mansfield  ores,  Pennsylvania,  98. 
Margerie  and  Heim,  cited  on  faults, 

18. 

Maricopa  Co.,  Ariz.,  228. 
Mariposa  Co.,  Cal.,  249. 
Mariposite,  249. 

Markhamville,  N.  B.,  manganese,  266. 
Marmora,  Can.,  arsenic  mine,  260. 

Gold  mines,  256. 
Marquette  district.  100. 
Marshall  tunnel,  Georgetown,  Colo., 

38. 
Maryland,  chromite,  261. 

Clinton  ore,  94. 

Gold  mines,  252. 

Limonite,  82. 
Marysvale,  Utah,  226. 
Marys ville,  Mont.,  222. 
Massachusetts,  lead  mines,  157. 

Limonite,  80-84. 

Spathic  ore  at  Gay  Head,  89. 
McGee,  W.  J.,  Appomattox  and  Co- 
lumbia formations,  5. 

On  joints,  13. 
Meagher  Co.,  Mont.,  222. 
Melaconite,  Keweenaw  Point,  142. 
Mendota  mines,    Keweenaw    Point, 

142. 
Menominee  district,  Lake  Superior, 

107. 
Mercury,  267-269. 

Mines,  California,  275. 


296 


INDEX. 


Mesabi  range,  Minnesota,  111,  112. 

Metacinnabarite,  267. 

Metamorphic     rocks,     defined     and 

roughly  classified,  6. 
Michigan,  copper,  139. 

Gold,  253. 

Limonite,  78. 

Marquette  district,  102-105. 

Menominee,  107,  108. 

Penokee-Gogebic,  108. 
Middletown,  Conn.,  lead  mine,  157. 
Milan,  N.  H.,  mines  of  pyrite,  131. 

Chalcopyrite,  134. 
Millerite,  269. 

Mine  la  Motte,  Mo.,  lead  mines,  158, 
159. 

Nickel,  271. 
Mineral    Point,   Wis.,    copper    ores, 

164. 
Mineville,   N.   Y.,    iron  mines,    121, 

122. 
Mine  waters  with  dissolved  metals, 

40. 
Minnesota  copper  mines,  143. 

Limonite,  78. 

Mesabi  range,  111. 

Titaniferous  ores,  281. 

Vermilion  district,  110,  111. 
Missabe.    See  Mesabi. 
Mississippi,    spathic    ores  at  Enter- 
prise, 89. 
Mississippi  Valley,  geology,  9. 

Lead  and  zinc  mines,  161. 

Relations  of  ore  bodies,  276. 
Missoula  Co.,  Mont.,  222. 
Missouri,  Cambrian  bed  hematite  in 
Crawford,    Dent,    and    Phelps 
Counties,  99. 

Copper  at  St.  Genevieve,  143. 

Iron  Mountain,  116. 

Lead  mines  of  southeastern  Mis- 
souri, 158. 

Limonite,  78. 

Lower  Carboniferous  red  hema- 
tite, 98. 

Pilot  Knob,  114. 

Tin,  274. 

Zinc  and  lead  in  the  southwest, 

166. 

Mitchell  Co.,  N.  C.,  iron  mines,  125. 
Mohave  Co.,  Ariz.,  228. 
Moisie,  Can.,  magnetite  sands  of,  128. 
Monarch  district,  Chaff ee  Co.,  Colo., 

186,  212. 

Monocline  defined,  11. 
Montana,  Butte,  136  137. 
Montana,  geology  of,  218. 

Iron  ore  at  Great  Falls,  74. 

Lead-silver  ores,  191, 192. 

Silver  and  gold  mines,  219-222. 


Montana,   spathic  iron  ore  at  Sand 

Coulee,  89. 
Tin,  274. 

Montville,  N.  J.,  123. 
Morenci,  Ariz.,  copper  district,  145. 
Moricke,  on  gold  in  Chilean  volcanic 

rocks,  25. 

Mosquito  range,  Colo.,  182. 
In  Park  Co.,  Colo.,  212. 
Mother  Lode,  C,il.,  249. 
Mount  Baldy,  Utah,  226. 
Mount  Davidson,  Nev  ,  233. 
Mount  Hope,  N.  J.,  123. 
Mount  Marshall,   near   Georgetown, 

Colo.,  214. 
Mount  McClellan,  Clear  Creek  Co., 

Colo.,  211. 

Mount  Prometheus,  Nev.,  232. 
Mount  Shasta,  Cal.,  241. 
Mule  Pass  Mountains,  Ariz.,  148. 
Mullica  Hill,  N.  J.,  bog  ore  with  vivi- 

ani'e,  74. 
Munroe,  H.  S.,  citation  from,  30. 

Cited  on  the  origin  of  magnetite, 

130. 
Scheme  of  classification   of    ore 

deposits,  52,53. 
Musconetcong  iron  belt,  New  Jersey, 

124. 

Nacemiento  copper  mines,  New  Mex- 
ico, 227. 
Nason,  F.  L.,  cited  on  the  geology  of 

the  Highlands,  N.  J.,  123. 
On  geology  near  Franklin  Fur- 
nace, N.  J.,  175. 
On  Missouri  geology,  282. 
On  Missouri  iron  ores,  118. 
Neck  of  igneous  rock  defined,  11. 
Neihart.  Mont.,  222. 
Nelson  Co.,  Va.,  tin,  274. 
Neocomian  beds,  California,  267. 
Nevada,  antimony,  259. 
Geology,  230. 
Lead-silver  mines,  196. 
Lovelock  nickel  mines,  271. 
New  Almaden,  Cal.,  mercury,  267. 
Newberry,  J.  S.,  cited  on  the  Cave 

Mine,  Utah,  195. 
On  Clinton  ore,  97. 
On  Silver  Reef,  Utah,  226. 
Scheme  of  classification  of  ore 

deposits,  48,  50. 
Newberry,  W.  E.,   cited  on  Aspen, 

Colo.,  188,  190. 
New  Brunswick,  antimony,  259. 

Manganese,  266. 
New  Brunswick,  N.  J.,  copper  mines, 

153. 

Newburyport,  Mass.,  lead  mine,   157. 
New  Caledonia  nickel,  271,  272. 


INDEX. 


29r 


New  England,  outline  of  geology,  7,  8. 
New  Hampshire  tin,  274. 
New  Idria,  Cal.,  mercury,  267,  268. 
New  Jersey  copper  ores,  153. 

Iron  mines.  123,  124. 

Limonite,  81. 

Outline  of  geology,  7,  8. 

Titaniferous  ores,  281. 

Zinc  mines,  175. 
New  Jersey  Zinc  and  Iron  Co.'s  mine, 

Franklin  Furnace,  N.  J.,  176. 
Newman    Hill,  Colo.,  banded  veins, 
35,  36. 

Figure  of  faulted  vein  at,  20. 

Lateral  enrichments,  37. 

Mines  of,  231. 
New  Mexico,  geology,  202. 

Lead-silver  mines,  181,  282. 

Silver  and  gold  mines,  202-204. 

Triassic  copper  ores,  154. 
Newton,  Amador  Co.,  Cal.,  copper, 

136. 

Newton  Co.,  Mo.,  zinc  mines,  167. 
New  York  copper  mine,  Arizona,  150. 
New  York,   iron  (bo^)    ore,    Staten 
Island,  74;  Rye,  74. 

Iron  mines  of  the  Highlands,  123. 
Literature,  124,  125. 

Iron  ore  of  Adirondacks,  120,  121. 
Literature,  122,  123. 

Lead  mines,  157,  158. 

Limonite,  80,  85. 

Outline  of  geology,  7,  8. 

Spathic  ore  of  Burden  mines,  89. 
at  Warwarsing,  91. 

Clinton  ore,  93. 

Jefferson  Co.,  99. 
NeyCo.,Nev.,  231. 
Niccolite,  269. 
Nickel  and  cobalt,  269-272. 
Nickel,  statistics,  271,  272. 
Nicholas,  W.,  cited  on  precipitation 

of  gold,  251. 
Nicholson,  F.,  on  the  St.  Genevieve, 

Mo.,  copper  mines,  144. 
Northampton,  Mass.,  lead  mine,  157. 
North  Carolina,  gold  mines,  252. 

Iron  (bog)  ore,  74. 

Limonite,  1,  84. 

Magnetite,  125. 
Literature,  125. 
Titaniferous  magnetite,  281. 

Nickel,  271. 

Spathic  ores,  89. 

Specular  ores,  114. 

Tin,  274. 
Nor  way,  nickel,  272. 

Titaniferous  ores,  281. 
Nova  Scotia,  Clinton  iron  ore,  97. 

Gold,  255. 


Nova  Scotia,  manganese,  266. 
Oat  Hill  mercury  mine,  267. 
Ogdensburg,  N.  J.,  174,  175-179. 
Ohio,  Clinton  ore,  92,  93. 
Limonite,  78. 
Spathic  ores,  88. 
Okanogan  Co.,  Wash.,  238. 
Old  Dominion  copper  mine,  Arizona, 

150. 
Olmstead,  I.,    cited  on   the  Burden 

mines,  New  York,  90. 
Olympic  Mountains,  238. 
Oneida  Co.,  Idaho,  223. 
Ontario,  arsenic  mine  at  Deloro,  260. 
Ontario  mine,  Utah,  225. 
Ontonagon,  Mich  ,  141. 
Ophir  Canon,  Utah,  194,  225. 
Oquirrh  Mountains,  Utah,  192,  225. 
Orange  Co.,  N.  Y.,  iron  mines,  123. 
Oregon,  geology,  239. 

Mercury,  267. 
Ore  Knob,  N.  C.,  copper  mines,  134, 

135. 

Ores,  minerals  forming,  23. 
Original  source  of,  23. 
Of  iron,  table  of,  70. 
Organic    matter  as    a    precipitating 

agent,  57. 
Orton,  E..  cited  on   dolomitization, 

22. 

Osmium,  with  platinum,  272. 
Ouachita  uplift  of  Arkansas,  170,  201, 

276. 

Ouray  Co.,  Colo.,  205. 
Owybee  Co.,  Idaho,  223. 
Oxford,  N.  J.,  123. 
Ozark  uplift,  7,  114,  170,  276. 
Pacific  slope,  geology,  10. 
Pahranagat  district,  Nev.,  231. 
Palmer  Hill  iron  mines,  N.  Y.,  122. 
Park  Co.,  Colo.,  212. 
Passaic  iron  belt,  New  Jersey,  124. 
Pearce,   R.,   bismuth    with    gold   in 

Colorado,  250. 
On  gold  ores  of  Gilpin  Co.,  Colo., 

214. 

Penfield,  S.  F.,  on  sperrylite,  272. 
Peninsula    copper  mines,  Michigan, 

141. 
Penrose,  R.  A.  F.,  on  manganese,  264- 

266. 

On  the  iron  ores  of  Arkansas,  279. 
Pennsylvania,  brown  hematites.  See 

under  Iron,  brown  hematite. 
Chromite,  261. 
Clinton  ore,  93. 
Lead  mines,  157. 
Limonite,  76,  77,  81,  84,  85. 

For  index  of  counties  see  un- 
der Iron  ores,  limonite. 


298 


INDEX. 


Pennsylvania,  Mansfield  ore,  98. 
Nickel,  270. 
Spathic  ores,  87. 

Penokee-Gogebic  district,  Lake  Su- 
perior, 108. 

Pequest  iron  belt,  New  Jersey,  124. 

Perkiomen  copper  mine,  Pennsyl- 
vania, 153. 

Phillips,  J.  A.,  scheme  of  classifica- 
tion of  ore  deposits,  49. 

Phoenix  copper  mine,  Michigan,  141. 

Phosphorus  in  iron  ores,  71,  72. 

Pilot  Knob,  Mo.,  114. 

Bibliography,  118,  119. 

Pima  Co.,  Ariz.,  229. 

Final  Co.,  Ariz.,  228. 

Pinches  and  swells  in  a  vein,  37. 

Pioche,  Nev.,  230. 

Pipe  clays  in  California  gravels,  246. 

Pitkin,  Colo.,  211. 

PiuteCo.,  Utah,  226. 

Placer  Co.,  Gal.,  iron  ores,  126. 
Chromite,  261. 

Placers,  243-248. 

Plateau  region  of  Wyoming,  216. 

Platinum,  272. 

Platoro,  Conejos  Co.,  Colo.,  212. 

Point  Orford,  Ore.,  240. 

Poorman  Lode,  Idaho. 

Portage  Lake,  Mich.,  141. 

Porter,  J.  B.,  cited  on  Clinton  ore,  97. 

Port  Henry,  N.  Y.,  iron  mines  near, 
121,  122. 

Posepny,  F. ,  on  origin  of  ore  deposits, 

282,  283. 

Cited  on  replacement  theory  for 
Raibl,  33. 

Prairie  region,  9. 

Of  Wyoming,  216. 

Prescott,  Ariz.,  151. 

Prickly  Pear  Gulch,  near  Helena, 
Mont.,  221,  245. 

Pride  of  the  West  mine,  Eagle  Co., 
Colo.,  211. 

Prime,  F.,  and  Von  Cotta,  scheme  of 
classification  of  ore  deposits, 
46,  47. 

Printer  Boy  mine,  T4eadville,  Colo., 
183. 

Psilomelane,  262. 

Puget  Sound,  238. 

Pumpelly,  R.,  cited  on  replacement, 

33. 

On  subaerial  decay,  59. 
On     Keweenaw    Point      copper 

mines,  142. 

Scheme    of  classification  of  ore 
deposits,  51,  52. 

Putnam  Co.,  N.  Y.,  iron  mines,  123. 

Pyrite,  131,  132. 


Pyrite,  literature,  132. 

Origin  of,  132. 
Pyrite  ore  bodies,  general  relations, 

276. 

Pyrolusite,  262. 
Pyrrhotite  with  nickel,  269. 
Quaquaversal  defined,  11. 
Quaco  Head,  N.  B.,  manganese,  266. 
Quebec,  bog  ores,  279. 

Iron  (bog)  ore.    See  Addenda. 
Quincy  copper  mine,  Mich.,  141. 
Quicksilver  (mercury),  267-269. 
Quogue,     Long     Island,    magnetite 

sands,  128. 
Radnor  ores,  i.e.,  Three  Rivers,  Can., 

279. 
Raibl,  Austria,   silver-lead  deposits, 

originating  by  replacement,  33. 
Rainbow  Lode,  Butte,  M^nt.,  220. 
Rainier  Mountain,  238. 
Ramapo  iron  belt,  N.  J.,  124. 
Ramshorn  mine,  Custer  Co.,  Idaho, 

223. 

Ranges  of  ore  deposits,  275,  276. 
Raymond  &  Ely  mine,  Pioche,  Nev., 

230. 

Raymond,  R.  W.,  277,  282. 
Red  Cliff  Eagle  Co.,  Colo.,  211. 
Red  Mountain,  Mont.,  220. 
Red  Mountain,  Ouray  Co.,  Colo.,  190. 
Red  River  region,  Kentucky,  77. 
Red  Rock,  San  Francisco,  manganese. 

266. 
Reese    River    district,  Nev.,  banded 

veins,  35. 
Geology  of,  232. 
Replacement   of   limestone   by    iron 

ores,  278,  279. 
Replacement,  method  of  vein  filling 

by,  33. 
Reyer,    E.,   on   the  Marquette    ores, 

106. 
Rico,  Dolores  Co.,  Colo.,  lead-s.'lver 

mines,  190. 

Riddle,  Ore.,  nickel  mines,  271. 
Rifting    in    granite    at    Cape    Ann, 

Mass.,  12. 

Rim  of  deep  gravels,  California,  245. 
Rio  Grande  Co.,  Colo.,  212. 
River  gravels,  with  gold,  243. 
Roaring  Fork  Creek,  Colo.,  188. 
Robert  E.  Lee  mine,  Leadville,  Colo., 

183. 
Robinson  mine,  Summit  Co.,  Colo., 

186. 

Rockbridge  Co.,  Va.,  tin,  274. 
Rock  Point,  Ore.,  nickel,  271. 
Rocks,  classification  of,  6. 

General  percentage  of  iron  oxide, 

72. 


INDEX. 


299 


Rocky  Mountain*,  geology,  9. 
Zinc  ores,  179. 

Rogers,  H.  D.,  on  geology  at  Frank- 
lin Furnace,  N.  J.,  175. 

Rolker,  C.  M.,  cited  on  Colorado  iron 

ores,  126. 
On  Silver  Reef,  Utah,  226. 

Rominger,  C.,  on  the  Marquette  dis- 
trict, 101,  102. 

Ropes  mine,  gold,  Michigan,  253. 

Rosenbusch,  H.,  cited  on  succession 
of  rock-forming  minerals,  24. 

Rosita,  Colo.,  212,  213. 

Rothpletz,  A.,  cited  on  oolites,  57. 

Rothwell,  R.  P. ,  on  Silver  Rt:ef ,  Utah, 
226. 

Roxbury,  Conn.,  spathic  ore,  91. 

Ruby,  Colo.,  211. 

Russell,  J.  C.,  cited  on  Clinton  ore, 
97. 

Russia,  platinum,  272. 

Sacramento  Valley,  243. 

Saguache  Co.,  Colo.,  207-209. 

Saline  Co.,  Ark.,  nickel,  271. 

Salt  Lake  Co.,  Utah,  225. 

San  Benito  Co.,  Cal.,  antimony,  259. 

San  Bernardino  Co.,   Cal.,  iron   ore, 
127. 

Sandberger,    F.,   cited  on  source  of 

ores,  25, 

Barite  in  limestone,  26. 
On  lateral  secretion,  30. 

San  Diego  Co.,  C«l.,  iron  ores,  127. 

San  Emigdio,  Kern  Co.,   Cal.,  anti- 
mony, 259. 

Sangre  de  Cristo  range,  Colorado,  212. 

Sandia  Mountains,  N.  M.,  204. 

Sanford  Lake,  titaniferous  ores,  New 
York,  280. 

San  Joaquin  Co.,  Cal.,  266. 

San  Juan  Co.,  Colo.,  205. 
Bismuth,  260. 

San  Juan  Mountains,  205. 

San  Juan  region,  Colorado,  205. 

San  Luis  Obispo  Co.  (Cal.)  chromite, 
261. 

San  Miguel  Co.,  Colo..  206,  245. 

Santa  Fe  Co  ,  N.  M.,  204. 
Placers  of,  245. 

Santa  Rita,  N.  M.,  copper  mines,  150, 
151. 

Santa  Rita  Mountains,  203. 

Saucon  Valley  zinc  mines,  Pennsyl- 
vania, 174,  175. 

Schmitt,  A.,  on  Missouri  iron  ores, 

118. 
On  replacement  theory  as  applied 

to  Missouri  iron  ores,  33. 
On  zinc  mines  of  southwestern 
Missouri,  167. 


Schapbach  in  the  Black  Forest,  veins 

at,  31. 
Schooley's  Mountain,  N.  J.,  iron  ores, 

281. 
Schuyler  copper  mine,  New  Jersey, 

153. 

Sebenius,  U. ,  on  Adirondack  titanif- 
erous ores,  280. 

Sedimentary  rocks  defined  and  rough- 
ly classified,  6. 

Forms  assumed  by,  10,  11. 
Segregated  veins,  as  applied  to  mag- 
netite, 281. 

Described,  60. 
Senarmontite,  259. 
Sevier  Co.,  Ark  ,  antimony,  259. 
Shasta  Co.,  Cal.,  chromite,  261. 
Shear  zones,  defined,  13. 
Sheet  of  igneous  rock,  defined,  11. 
Shepherd  Mountain,  Mo.,  116. 
Shumagin,  Alaska,  254. 
Siderite,  iron  ore,  86-91. 
Siegenite,  Mine  la  Motte,  Mo.,  271. 
Sierra  Co.,  Cal.,  iron  ore,  126. 
Sierra  Nevada,  chromite,  261. 
Sierra  Nevada  in  California,  241. 

Recent  geological  history,  282. 
Sigmoid  fold,  defined,  11. 
Silliman,  B.,  on  gold  quartz,  248. 
Siluro-Cambrian  limomtes,  276. 
Silver  and  gold,  mode  of  occurrence, 

199.  200. 

Silver  belt  of  Utah,  275, 
Silver  Bow  Co.,  Mont.,  220. 
Silver  Bow  Creek,  Butte,  Mont.,  136. 
Silver,  California,  242. 
Silver  City,  Idaho,  223. 
Silver  Cliff,  Colo.,  212,  213, 
Silver  Islet,  Lake  Superior,   vein  il- 
lustrating lateral  secretion,  31. 

Literature,  31. 

Mines,  201. 

Silver  King  mine,  Arizona,  228. 
Silver  minerals,  200. 
Silver  Plume,  Colo.,  214. 
Silver  Reef,  Utah,  154,  226. 
Silverton,  Colo.,  207. 
Silver,  Washington,  239. 
Slayback  Lode,  New  Mexico,  204. 
Slickensides  or  slips,  defined,  18,  19. 
Smyth,  C.  H.,  Jr.,  on  Clinton  ore,  97. 
Smithfield  iron  mine,  Colorado,  126. 
Smuggler    Mountain,    near    Aspen, 

Colo.,  189. 
Snake  River,  Idaho,  basalt,  222. 

Placers,  Idaho,  245. 
Socorro  Co.,  N.  M.,  204. 
Sonora,  Mex.,  antimony,  260. 
South  Dakota,  lead-silver  ores,  191. 

Geology,  216. 


300 


INDEX. 


South  Dakota,  source  of  ore,  277. 

Southern  States,  gold,  252. 

South  Mountain,  Perm.,  iron  mines, 

123,  125. 

Literature,  124,  125. 
South  Park,  Colo.,  212. 
South  Wallingford,  Vt.,  manganese, 

263. 

Spanish  Peaks,  Colo.,  212. 
Spathic  iron  ore,  86-91. 
Spenceville,  Cal.,  copper  mines,  136. 
Sperry,  F.  L.,  discovered  sperrylite, 

272. 

Sperrylite,  272. 

St.  Clair  limestone,  Arkansas,  265. 
St.  Fran£ois  Co.,  Mo.,  gash  veins,  165. 
St.  Genevieve,  Mo.,    copper    mines, 

143. 

Geology,  282. 
St.  Lawrence  Co.,  N.  Y.,  lead  mines, 

156. 
Stanley -Browne,  J.,  cited  on  gold  in 

sea  beaches,  240. 
Stannite,  273. 

Star  District,  Utah,  iron  mines,  128. 
Steamboat  Springs,  Nev.,  illustrate 

infiltration  by  ascension,  32. 
Mercury  mines,  267. 
Stein  Mountains,  Ore.,  239. 
Stelzner,  A.  W.,  cited  on  source  of 

ores,  25. 
Sterling  Hill,   zinc  mines,   Ogdens- 

burg,  N.  J.,  174-178. 
Stevens  Co.,  Wash.,  gold,  238. 
Stibnite,  259. 

Stillwater  Co.,  Wyo.,  gold  mines,  216. 
Stobie  nickel  mine,  Sudbury,   Ont., 

270. 

Stokes  Co.,  N.  C.,  magnetite,  125. 
Storey  Co.,  Nev.,  232. 
Strahan,  A.,  cited  on  explosive  slick- 

ensides,  19. 
Stream  tin,  273. 
Structure  of  veins,  35. 
Sudbury,  Ontario,  131. 

Nickel,  270. 

Sullivan  Co.,  N.  Y.,  lead  mines,  158. 
Sullivan,  Me  ,  silver  mines,  201. 
Sulphur  Bank,  Cal.,  mercury  mine, 

267. 
Summit  Co.,  Colo.,  211. 

Ten  Mile  district,  185, 186. 
Summit  Co  ,  Utah,  lead-silver,  195. 

Silver  mines,  225. 
Summit   district,    Rio   Grande   Co., 

Colo.,  212. 

Sunrise,  Wyo.,  copper,  152. 
Sweden,  lake  ore,  75. 
Nickel,  272. 
Titaniferous  ores,  281. 


Sweetwater  district,  Wyo.,  245. 
Sylvanite  mine,  Gothic,  Colo.,  211. 
Syncline  denned,  11. 

Cause  of  cavities,  14. 
Tacoma  Mountain,  238. 
Tamarack  copper  mines,   Michigan, 

Tarr,  R.  S.,  on  rifting,  12. 
Telegraph  mine,  Utah,  194. 
Telluride  ores,  Colorado,  214. 
Tellurides  in  gold  quartz,  248. 
Temescal  tin  mines,  California,  274. 
Tern  Pahute  district,  Nev.,  231. 
Ten  Mile  district,  Colo.,  185,  211. 
Tennessee,  Clinton  ore,  94. 
Tennessee  limonite,  78,  82. 
Tenny  Cape,  N.  S.,  manganese,  266. 
Terrane  defined,  5. 
Texas,  copper,  Llano  Co.,  139. 
Limonite,  78. 
Triassic  or  Peruvian  copper  ores, 

154. 
Thiess-Hutchins    antimony     mines, 

Nev.,  259. 

Three  Rivers,  Can.,  bog  ores,  279. 
Thunder  Bay,  Lake  Superior,  202. 
Tilly  Foster  iron  mine,  N.  Y.,  123, 

124. 

Tin,  273,  274. 
Tin  Cup,  Colo.,  211. 
Tintic  district  copper  mines,   Utah, 

152. 

Lead- silver,  194. 
Other  silver  mines,  225. 
Titaniferous  magnetite,  122,  280,  281. 
Tombstone  district,  Arizona,  229. 
Tooele  Co. ,  Utah,  194,  225. 
Torrington,  Conn.,  nickel  mine,  270. 
Tourtelotte  Park,  near  Aspen,  Colo., 

188. 

Toyabe  range,  Nev.,  232. 
Treadwell  mine,  Alaska,  255. 
Triassic  copper  ores,  152-154. 

Copper  mines,  general  relations, 

276. 
Trotter  zinc  mine,  Franklin  Furnace, 

N.  J.,  176. 

Tucson,  Arizona,  229. 
Tuolumne  Co.,  Cal.,  249. 
Tuscarora  district,  Nev.,  232. 
Tybo,  Nev.,  231. 
Ueberroth  zinc  mine,  Pennsylvania, 

174. 

Uintah  Mountains,  10,  224. 
Ulster  Co.,  N.  Y.,  lead  mines,  158. 
United  States  Antimony  Co.,  Phila- 
delphia, 259. 
United    States    Geological    Survey, 

terms    used  by  in    geological 

classification,  4. 


INDEX. 


301 


United  States,  general  geology,  7-10. 

General  topography,  6,  7. 
Uralitization  in  the  rocks  of  the  Corn- 
stock  Lode,  236. 
Utah,  antimony,  259. 
Copper,  152. 
Geology,  224. 
Lead-silver  ores,  192-196. 
Limonite,  79. 
Magnetite,  128. 
Silver  mines,  275. 
Triassic  copper  ores,  154. 
Vadose  circulations,  283. 
Van  Diest,  P.   H.,  on  Boulder  Co., 

Colo.,  214. 

Van  Dyck,  F.  C.,  analysis  by,  177. 
Van  Hise,   C.  R.,  cited  on  replace- 
ment, 33. 
On  the  Marquette  district,  101, 

102. 
On  the  Penokee  Gogebic  district, 

Lake  Superior,  109. 
Veins,  methods  of  filling,  28. 
Verde  River,  Ariz.,  151. 
Vermilion    district,    Lake    Superior, 

110. 
Vermilion  Lake  iron  ores,  origin  of, 

60,  61. 
Vermont,  copper  ores,  134,  135. 

Limonite,  80. 
Vershire,  Vt.,  mines  of  pyrite,  131. 

Chalcopyrite,  134. 
Virginia,  Clinton  ore,  94. 

Limonite  or  brown  hematite,  77, 

82. 

Louisa  Co.,  pyrite,  131. 
Magnetite,  125. 
Manganese,  263. 
Titaniferous  ores,  281. 
Wythe  Co.,  zinc  and  lead,  172. 
Virginia  City,  Mont.,  219. 
Von  Herder,  on  filling  of  veins,  28. 
Von  Richthofen,    on  the  Comstock 

Lode,  233-236. 
Vuggs  of  a  vein,  35. 
Wadsworth,  M  E.,  on  the  Marquette 

district,  101,  102. 
On  Silver  Islet,  202. 
On  the  classification  of  ore  de- 
posits, 278. 

Origin  of  the  ores,  104. 
Wagon  Wheel  Gap,  Colo.,  209. 
Wall  rock  of  veins,  precipitating  in- 
fluence of,  31. 

Wardner,  Idaho,  lead-silver  ores,  192. 
Warren  or    Bisbee    copper    district, 

Arizona,  148. 

Wasatch  Mountains,  9,  224. 
Washington  Co.,  Mo.,  lead  and  zinc 
mines,  165. 


Washington,  geology,  238. 

Washoe  Co.,  Nev.,  232. 

Webb  City,  Mo.,  zinc  and  lead  mines 

near,  166-171. 
Webster,  Jackson  Co.,  N.  C.,  nickel, 

271. 

Weed,  W.  H.,  cited  on  siliceous  sin- 
ters, 57. 

Weissenbach,  Von,  scheme  of  clas- 
sification of  ore  deposits,  44. 
Wells,  H.  L..  on  sperrylite,  272. 
Wendt,  A.   F.,   on    Arizona   copper 

mines,  147. 

West  port,  N.  Y.,  iron  mines,  120. 
West  Virginia,  Clinton  ore,  94. 
Oriskany,  red  hematite,  98. 
Spathic  ores,  88. 
Wet  Mountain  Valley,  Custer    Co., 

Colo.,  212. 
Wheatley  lead  mine,  Pennsylvania, 

157. 

White  Pine  Co.,  Nev.,  231. 
Whitney,  J.  D.,  cited  on  Missouri  ores, 

118. 

On  California  gravels,  247. 
On  gold  veins,  250. 
On    lead  and  zinc    veins  of  the 

Mississippi  Valley,  163. 
On    Washington   Co.,    Missouri, 

lead  and  zinc  mines,  165. 
Scheme  of   classification  of  ore 

deposits,  48. 
Wickes,  Mont.,  lead-silver  mines,  192, 

220. 
Williams,  J.  F.,  on  Arkansas  bauxite, 

258. 
Willow  Creek,   near  Creede,    Colo., 

209. 
Wiltsee,  E.,  on  the  Half  Moon  mine, 

Pioche,  Nev.,  230. 
Winchell,  N.  H.  and  H.  V.,  cited  on 

origin  of  Vermilion  Lake  iron 

ores,  61. 

Winchell,  N.  H.,  cited  on  the  Ver- 
milion Lake  district,  110. 
Winchell,  H.  V.,  on  the  origin  of  the 

ore,  111. 

On  the  Mesabi  ores,  113. 
Winslow,   A.,  on  Missouri  geology, 

282. 

Winslow,  tin,  274. 
Wisconsin,  Clinton  ore,  Dodge  Co., 

92. 

Lead  and  zinc  mines,  161. 
Menominee  district,  107,  108. 
Penokee-Gogebic    district,     108, 

109. 
Wood  River  mines,  Idaho,  lead-silver, 

191,  223. 
Woods  mine,  chromite,  261. 


302 


INDEX. 


Wright,  C.  E.,  origin  of  Lake  Supe- 
rior ores,  106. 
"Wyoming  copper  mines,  152. 

Geology  of,  216. 

Iron  mines,  126. 

Iron  ore  near  Fort  Laramie,  114. 

Spathic  iron  ore,  89. 

Specular  ore  near  Fort  Laramie, 
114. 

Tin  ores,  274. 

Titaniferous  ores,  281. 
Wythe  Company  zinc  mines,  282. 
Whyte  Co.,  Va.,  zinc  and  lead  mines, 

172. 
Xenogenites  of  Posepny,  283. 


Yakima  Co.,  Wash.,  gold,  238. 
Yakutat  Bay,  Alaska,  240. 
Yarmouth,  N.  S.,  255. 
Yavapai  Co.,  Ariz.,  228. 
York  Co.,  N.  B.,  antimony,  259. 
York  Co.,  Penn.,  iron  mines,  127. 
Yuma  Co.,  Ariz.,  228,  229. 
Yuba  River,  California,  282. 
Yukon  River,  Alaska,   253. 
Zinc  minerals,  174. 

Statistics,  180. 

Zirkel,  F.,  on  the  rocks  of  the  Corn- 
stock  Lode,  236. 
Zone  of  oxidized  ores  in  a  vein,  38. 

Of  sulphides,  38. 


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